Exchange 2013 -> 2016 Move Requests Stuck

I'm trying to migrate users from Exchange 2013 to Exchange 2016 but when I create a move request, even with only 1 mailbox in the queue, with a size of a few kilobytes, it'll inevitably end up at RelinquishedWlmStall.

There are no performance issues on either server, and I initially ran the move overnight. Any pointers to solutions or where I could gather more information about the issue?

Here's what I've tried so far:

• Changed HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\MSExchange ResourceHealth.
• Used the Highest and Emergency priorities.
• Adjusted MSExchangeMailboxReplication.exe.config.
• Executed Get-ExchangeServer | ForEach {New-SettingOverride -Component "WorkloadManagement" -Name "$_ MRS Override" -Server $.Name -Section MailboxReplicationService -Reason "$ Temporary Move" -Parameters Classification=Urgent -MinVersion 15.0}
• Restarted both servers multiple times.

Here are the move statistics:

ArchiveGuid                            :
Status                                 : InProgress
StatusDetail                           : RelinquishedWlmStall
SyncStage                              : None
Flags                                  : IntraOrg, Pull
RequestStyle                           : IntraOrg
Direction                              : Pull
IsOffline                              : False
Protect                                : False
DoNotPreserveMailboxSignature          : False
Priority                               : Normal
WorkloadType                           : Local
Suspend                                : False
SuspendWhenReadyToComplete             : False
IgnoreRuleLimitErrors                  : False
RecipientTypeDetails                   : UserMailbox
SourceVersion                          : Version 15.0 (Build 1320.0)
TargetVersion                          : Version 15.1 (Build 225.0)
SourceArchiveDatabase                  :
SourceArchiveVersion                   :
SourceArchiveServer                    :
TargetArchiveDatabase                  :
TargetArchiveVersion                   :
TargetArchiveServer                    :
RemoteHostName                         :
RemoteGlobalCatalog                    :
StartAfter                             :
CompleteAfter                          :
RemoteCredentialUsername               :
RemoteDatabaseName                     :
RemoteDatabaseGuid                     :
RemoteArchiveDatabaseName              :
RemoteArchiveDatabaseGuid              :
TargetDeliveryDomain                   :
ArchiveDomain                          :
BadItemLimit                           : 10
BadItemsEncountered                    : 0
LargeItemLimit                         : 0
LargeItemsEncountered                  : 0
AllowLargeItems                        : True
StartTimestamp                         :
InitialSeedingCompletedTimestamp       :
FinalSyncTimestamp                     :
CompletionTimestamp                    :
SuspendedTimestamp                     :
OverallDuration                        : 05:07:15.8805147
TotalFinalizationDuration              : 00:00:00
TotalDataReplicationWaitDuration       : 00:00:00
TotalSuspendedDuration                 : 00:00:00
TotalFailedDuration                    : 00:00:00
TotalQueuedDuration                    : 00:02:07.1040967
TotalInProgressDuration                : 01:50:11.4364136
TotalStalledDueToCIDuration            : 00:45:05.4836894
TotalStalledDueToHADuration            : 00:00:00
TotalStalledDueToMailboxLockedDuration : 00:00:00
TotalStalledDueToReadThrottle          : 00:00:00
TotalStalledDueToWriteThrottle         : 00:00:00
TotalStalledDueToReadCpu               : 00:00:00
TotalStalledDueToWriteCpu              : 00:00:00
TotalStalledDueToReadUnknown           : 00:00:00
TotalStalledDueToWriteUnknown          : 00:00:00
TotalTransientFailureDuration          : 00:00:00
TotalProxyBackoffDuration              : 00:00:00
TotalIdleDuration                      : 00:40:18.5876769
MRSServerName                          :
TotalMailboxSize                       : 64.08 MB (67,188,711 bytes)
TotalMailboxItemCount                  : 295
TotalArchiveSize                       :
TotalArchiveItemCount                  :
BytesTransferred                       : 0 B (0 bytes)
BytesTransferredPerMinute              : 0 B (0 bytes)
ItemsTransferred                       : 0
PercentComplete                        : 0
CompletedRequestAgeLimit               : 7.00:00:00
PositionInQueue                        :
InternalFlags                          : None
FailureCode                            :
FailureType                            :
FailureSide                            :
Message                                : Informational: The request has been temporarily postponed due to unfavorable
                                         server health or budget limitations. MRS will attempt to continue processing
                                         the request again after ****.
FailureTimestamp                       :
IsValid                                : True
ValidationMessage                      :
DiagnosticInfo                         :
Report                                 :
ObjectState                            : New

Here's a cleaned-up report:

[EXCHANGE2013] '' created move request.
[EXCHANGE2016] The Microsoft Exchange Mailbox Replication service 'exchange2016.hostname' (15.1.225.37 caps:7FFF) is examining the request.
[EXCHANGE2016] Connected to target mailbox 'uuid1 (Primary)', database 'Target Database', Mailbox server 'exchange2016.hostname' Version 15.1 (Build 225.0).
[EXCHANGE2016] Connected to source mailbox 'uuid1 (Primary)', database 'Source Database', Mailbox server 'exchange2013.hostname' Version 15.0 (Build 1320.0), proxy server 'exchange2013.hostname' 15.0.1320.0 caps:0400001F7FFFFFCB07FFFF.
[EXCHANGE2016] Relinquishing job because of large delays due to unfavorable server health or budget limitations.
[EXCHANGE2016] The Microsoft Exchange Mailbox Replication service 'exchange2016.hostname' (15.1.225.37 caps:7FFF) is examining the request.
[EXCHANGE2016] Connected to target mailbox 'uuid1 (Primary)', database 'Target Database', Mailbox server 'exchange2016.hostname' Version 15.1 (Build 225.0).
[EXCHANGE2016] Connected to source mailbox 'uuid1 (Primary)', database 'Source Database', Mailbox server 'exchange2013.hostname' Version 15.0 (Build 1320.0), proxy server 'exchange2013.hostname' 15.0.1320.0 caps:0400001F7FFFFFCB07FFFF.
[EXCHANGE2016] Relinquishing job because of large delays due to unfavorable server health or budget limitations.
[EXCHANGE2016] The Microsoft Exchange Mailbox Replication service 'exchange2016.hostname' (15.1.225.37 caps:7FFF) is examining the request.
[EXCHANGE2016] Connected to target mailbox 'uuid1 (Primary)', database 'Target Database', Mailbox server 'exchange2016.hostname' Version 15.1 (Build 225.0).
[EXCHANGE2016] Connected to source mailbox 'uuid1 (Primary)', database 'Source Database', Mailbox server 'exchange2013.hostname' Version 15.0 (Build 1320.0), proxy server 'exchange2013.hostname' 15.0.1320.0 caps:0400001F7FFFFFCB07FFFF.
[EXCHANGE2016] Relinquishing job because of large delays due to unfavorable server health or budget limitations.
[EXCHANGE2016] The Microsoft Exchange Mailbox Replication service 'exchange2016.hostname' (15.1.225.37 caps:7FFF) is examining the request.
[EXCHANGE2016] Connected to target mailbox 'uuid1 (Primary)', database 'Target Database', Mailbox server 'exchange2016.hostname' Version 15.1 (Build 225.0).
[EXCHANGE2016] Connected to source mailbox 'uuid1 (Primary)', database 'Source Database', Mailbox server 'exchange2013.hostname' Version 15.0 (Build 1320.0), proxy server 'exchange2013.hostname' 15.0.1320.0 caps:0400001F7FFFFFCB07FFFF.
[EXCHANGE2016] The Microsoft Exchange Mailbox Replication service 'exchange2016.hostname' (15.1.225.37 caps:7FFF) is examining the request.
[EXCHANGE2016] Connected to target mailbox 'uuid1 (Primary)', database 'Target Database', Mailbox server 'exchange2016.hostname' Version 15.1 (Build 225.0).
[EXCHANGE2016] Connected to source mailbox 'uuid1 (Primary)', database 'Source Database', Mailbox server 'exchange2013.hostname' Version 15.0 (Build 1320.0), proxy server 'exchange2013.hostname' 15.0.1320.0 caps:0400001F7FFFFFCB07FFFF.
[EXCHANGE2016] Relinquishing job because of large delays due to unfavorable server health or budget limitations.

And another related error I could find:

MigrationTransientException: Failed to communicate with the mailbox database. --> Failed to communicate with the mailbox database. --> MapiExceptionMdbOffline: Unable to make connection to the server. ‎(hr=0x80004005, ec=1142)‎ Diagnostic context: Lid: 41192 dwParam: 0x1 Lid: 63464 Lid: 34792 StoreEc: 0x6AB Lid: 51176 StoreEc: 0x80040115 Lid: 48104 Lid: 39912 StoreEc: 0x80040115 Lid: 41192 dwParam: 0x2 Lid: 49384 Lid: 51176 StoreEc: 0x476 Lid: 48104 Lid: 39912 StoreEc: 0x476 Lid: 41192 dwParam: 0x0 Lid: 49064 dwParam: 0x1 Lid: 37288 StoreEc: 0x6AB Lid: 49064 dwParam: 0x2 Lid: 38439 EMSMDBPOOL.EcPoolConnect called [length=48] Lid: 54823 EMSMDBPOOL.EcPoolConnect returned [ec=0x476][length=20][latency=31] Lid: 53361 StoreEc: 0x476 Lid: 51859 Lid: 33649 StoreEc: 0x476 Lid: 43315 Lid: 58225 StoreEc: 0x476 Lid: 39912 StoreEc: 0x476 Lid: 54129 StoreEc: 0x476 Lid: 50519 Lid: 59735 StoreEc: 0x476 Lid: 59199 Lid: 27356 StoreEc: 0x476 Lid: 65279 Lid: 52465 StoreEc: 0x476 Lid: 60065 Lid: 33777 StoreEc: 0x476 Lid: 59805 Lid: 52487 StoreEc: 0x476 Lid: 19778 Lid: 27970 StoreEc: 0x476 Lid: 17730 Lid: 25922 StoreEc: 0x476

The error means what it says - there is a problem with the servers communicating. I have seen AV do this before - particularly AVAST, but also some others. If you have file level AV on the servers check it has the correct exclusions.