One system is stuck on an older Cumulative Update

I've set up a Service Fabric cluster on Azure, which is built on top of Virtual machine scale sets. It has two scale sets, one with three nodes and one with a single node. Both scale sets run WindowsServer 2016-Datacenter-Server-Core, the only difference is that the one with a single node runs on a cheaper VM size.

I managed to install KB4093119 (OS Build 14393.2189) and KB4093120 (OS Build 14393.2214) on the three identical nodes via sconfig, but the single node is stuck on KB4088889 (OS Build 14393.2155), it says there are no updates available:

Search for for (A)ll updates or (R)ecommended updates only? a

Searching for all applicable updates...

List of applicable items on the machine:

There are no applicable updates.

The three identical nodes have this output from systeminfo:

Hotfix(s):                 5 Hotfix(s) Installed.
                           [01]: KB3192137
                           [02]: KB4049065
                           [03]: KB4089510
                           [04]: KB4093137
                           [05]: KB4093120

The single node has this output from systeminfo:

Hotfix(s):                 4 Hotfix(s) Installed.
                           [01]: KB3192137
                           [02]: KB4049065
                           [03]: KB4089510
                           [04]: KB4088889

This is the Windows Update log from the most recent update attempt:

2018/05/03 13:05:50.9029890 956   3128  Shared          * START * Service startup
2018/05/03 13:05:50.9096384 956   3128  Agent           WU client version 10.0.14393.2155
2018/05/03 13:05:50.9098252 956   3128  Agent           SleepStudyTracker: Machine is non-AOAC. Sleep study tracker disabled.
2018/05/03 13:05:50.9098846 956   3128  Agent           Base directory: C:\Windows\SoftwareDistribution
2018/05/03 13:05:50.9101255 956   3128  Agent           Datastore directory: C:\Windows\SoftwareDistribution\DataStore\DataStore.edb
2018/05/03 13:05:51.1046025 956   3128  Shared          UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2018/05/03 13:05:51.1046218 956   3128  Shared          UpdateNetworkState Ipv4, cNetworkInterfaces = 1.
2018/05/03 13:05:51.1050846 956   3128  Shared          Network state: Connected
2018/05/03 13:05:51.1492758 956   3128  Misc            LoadHistoryEventFromRegistry completed, hr = 8024000C
2018/05/03 13:05:51.1506450 956   3780  Agent           Initializing global settings cache
2018/05/03 13:05:51.1506455 956   3780  Agent           WSUS server: NULL
2018/05/03 13:05:51.1506458 956   3780  Agent           WSUS status server: NULL
2018/05/03 13:05:51.1506462 956   3780  Agent           Alternate Download Server: NULL
2018/05/03 13:05:51.1506465 956   3780  Agent           Fill Empty Content Urls: No
2018/05/03 13:05:51.1506469 956   3780  Agent           Target group: (Unassigned Computers)
2018/05/03 13:05:51.1506473 956   3780  Agent           Windows Update access disabled: No
2018/05/03 13:05:51.1512557 956   3780  Agent               Timer: 29A863E7-8609-4D1E-B7CD-5668F857F1DB, Expires 2018-05-03 15:33:28, not idle-only, not network-only
2018/05/03 13:05:51.1571467 956   3128  Shared          UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2018/05/03 13:05:51.1571518 956   3128  Shared          UpdateNetworkState Ipv4, cNetworkInterfaces = 1.
2018/05/03 13:05:51.1571563 956   3128  Shared          Power status changed
2018/05/03 13:05:51.1572517 956   3128  Agent           Initializing Windows Update Agent
2018/05/03 13:05:51.1574857 956   3128  DownloadManager Download manager restoring 0 downloads
2018/05/03 13:05:51.1582212 956   3128  Agent           CPersistentTimeoutScheduler | GetTimer, returned hr = 0x00000000
2018/05/03 13:05:51.1751105 956   3880  Shared          Effective power state: AC
2018/05/03 13:05:51.1751113 956   3880  DownloadManager Power state change detected. Source now: AC
2018/05/03 13:05:51.2628123 956   3780  Agent           * START * Queueing Finding updates [CallerId = <<PROCESS>>: cscript.exe  Id = 1]
2018/05/03 13:05:51.2628174 956   3780  Agent           Added service 00000000-0000-0000-0000-000000000000 to sequential scan list
2018/05/03 13:05:51.2657024 956   4852  Agent           * END * Queueing Finding updates [CallerId = <<PROCESS>>: cscript.exe  Id = 1]
2018/05/03 13:05:51.2682917 956   4852  Agent           * START * Finding updates CallerId = <<PROCESS>>: cscript.exe  Id = 1
2018/05/03 13:05:51.2682926 956   4852  Agent           Online = Yes; AllowCachedResults = No; Ignore download priority = No
2018/05/03 13:05:51.2682933 956   4852  Agent           Criteria = IsInstalled=0 and Type='Software'""
2018/05/03 13:05:51.2682963 956   4852  Agent           ServiceID = {00000000-0000-0000-0000-000000000000} Third party service
2018/05/03 13:05:51.2682968 956   4852  Agent           Search Scope = {Machine}
2018/05/03 13:05:51.2682995 956   4852  Agent           Caller SID for Applicability: S-1-5-21-2687739569-3004106656-2140684595-500
2018/05/03 13:05:51.2683001 956   4852  Agent           RegisterService is set
1601/01/01 00:00:00.0000000 2288  4388                  Unknown( 12): GUID=eb73583d-5481-33b4-202d-9bb270eddffa (No Format Information found).
2018/05/03 13:05:51.2711175 956   4852  Misc            Got 9482F4B4-E343-43B6-B170-9A65BC822C77 redir SecondaryServiceAuth URL: 117cab2d-82b1-4b5a-a08c-4d62dbee7782""
2018/05/03 13:05:51.2721640 956   4852  SLS             CoCreateInstance Failed: hr = 0x80040154
2018/05/03 13:05:51.2721664 956   4852  Agent           Failed to retrieve SLS response data for service 117cab2d-82b1-4b5a-a08c-4d62dbee7782, error = 0x80040154
2018/05/03 13:05:51.2721688 956   4852  Agent           Caller Service Recovery failed to opt in to service 117cab2d-82b1-4b5a-a08c-4d62dbee7782, hr=0X80040154
2018/05/03 13:05:51.2742668 956   4852  Misc            Got 9482F4B4-E343-43B6-B170-9A65BC822C77 redir Client/Server URL: https://fe2.update.microsoft.com/v6/ClientWebService/client.asmx""
2018/05/03 13:05:51.9867532 956   4852  ProtocolTalker  ServiceId = {9482F4B4-E343-43B6-B170-9A65BC822C77}, Server URL = https://fe2.update.microsoft.com/v6/ClientWebService/client.asmx
2018/05/03 13:05:51.9868666 956   4852  ProtocolTalker  OK to reuse existing configuration
2018/05/03 13:05:51.9868694 956   4852  ProtocolTalker  Existing cookie is valid, just use it
2018/05/03 13:05:52.6163585 956   4852  WebServices     Auto proxy settings for this web service call.
2018/05/03 13:06:42.0084185 956   4852  ProtocolTalker  SyncUpdates round trips: 2
2018/05/03 13:06:42.0084199 956   4852  ProtocolTalker  Sync of Updates 0x8024402f
2018/05/03 13:06:42.0092829 956   4852  ProtocolTalker  SyncServerUpdatesInternal failed 0x8024402f
2018/05/03 13:06:42.0117237 956   4852  Agent           Failed to synchronize, error = 0x8024402F
2018/05/03 13:06:42.0605156 956   4852  Agent           Exit code = 0x8024402F
2018/05/03 13:06:42.0605448 956   4852  Agent           * END * Finding updates CallerId = <<PROCESS>>: cscript.exe  Id = 1
1601/01/01 00:00:00.0000000 2288  5116                  Unknown( 16): GUID=eb73583d-5481-33b4-202d-9bb270eddffa (No Format Information found).
1601/01/01 00:00:00.0000000 2288  5116                  Unknown( 17): GUID=eb73583d-5481-33b4-202d-9bb270eddffa (No Format Information found).
1601/01/01 00:00:00.0000000 2288  5116                  Unknown( 19): GUID=eb73583d-5481-33b4-202d-9bb270eddffa (No Format Information found).
1601/01/01 00:00:00.0000000 2288  5116                  Unknown( 20): GUID=eb73583d-5481-33b4-202d-9bb270eddffa (No Format Information found).
1601/01/01 00:00:00.0000000 2288  4388                  Unknown( 10): GUID=fe1b6309-dedb-392e-308c-ec757efded1a (No Format Information found).

The issue has resolved itself, the most recent CU was available for installation. So I guess the answer here is to just wait a couple weeks.