Process Explorer not displaying the 32-bit stack for 32-bit processes on Win10 x64

If I use Process Explorer to view the call stacks of 32-bit processes on my 64-bit Windows 10 system, Process Explorer only shows the 64-bit (upper) part of the call stack and not the more interesting (lower) 32-bit part. For example, the call stack of the main thread of a 32-bit wmplayer.exe process shows:

ntoskrnl.exe!KiSwapContext+0x76
ntoskrnl.exe!KiSwapThread+0x2c6
ntoskrnl.exe!KiCommitThreadWait+0x13b
ntoskrnl.exe!KeWaitForSingleObject+0x1ff
ntoskrnl.exe!KiSchedulerApc+0x30a
ntoskrnl.exe!KiDeliverApc+0x27b
ntoskrnl.exe!KiSwapThread+0x501
ntoskrnl.exe!KiCommitThreadWait+0x13b
ntoskrnl.exe!KeWaitForSingleObject+0x1ff
ntoskrnl.exe!KeWaitForMultipleObjects+0x4b5
win32kfull.sys!xxxRealSleepThread+0x32a
win32kfull.sys!xxxSleepThread2+0xa0
win32kfull.sys!xxxRealInternalGetMessage+0xf19
win32kfull.sys!NtUserGetMessage+0x8c
ntoskrnl.exe!KiSystemServiceCopyEnd+0x13
wow64win.dll!NtUserGetMessage+0x14
wow64win.dll!whNtUserGetMessage+0x30
wow64.dll!Wow64SystemServiceEx+0x153
wow64cpu.dll!ServiceNoTurbo+0xb
wow64cpu.dll!BTCpuSimulate+0x9
wow64.dll!RunCpuSimulation+0xa
wow64.dll!Wow64LdrpInitialize+0x120
ntdll.dll!LdrpInitializeProcess+0x1887
ntdll.dll!_LdrpInitialize+0x4aa45
ntdll.dll!LdrpInitialize+0x3b
ntdll.dll!LdrInitializeThunk+0xe
0x0000000000000000

Whereas the call stack for a 64-bit wmplayer.exe process (C:\Program Files\Windows Media Player\wmplayer.exe) is complete and also contains the calls in application code:

ntoskrnl.exe!KiSwapContext+0x76
ntoskrnl.exe!KiSwapThread+0x2c6
ntoskrnl.exe!KiCommitThreadWait+0x13b
ntoskrnl.exe!KeWaitForSingleObject+0x1ff
ntoskrnl.exe!KiSchedulerApc+0x30a
ntoskrnl.exe!KiDeliverApc+0x27b
ntoskrnl.exe!KiSwapThread+0x501
ntoskrnl.exe!KiCommitThreadWait+0x13b
ntoskrnl.exe!KeWaitForSingleObject+0x1ff
ntoskrnl.exe!KeWaitForMultipleObjects+0x4b5
win32kfull.sys!xxxRealSleepThread+0x32a
win32kfull.sys!xxxSleepThread2+0xa0
win32kfull.sys!xxxRealInternalGetMessage+0xf19
win32kfull.sys!NtUserGetMessage+0x8c
ntoskrnl.exe!KiSystemServiceCopyEnd+0x13
win32u.dll!NtUserGetMessage+0x14
USER32.dll!GetMessageW+0x2b
wmp.dll!Ordinal3002+0x731
wmp.dll!Ordinal3002+0x65f
wmp.dll!Ordinal3000+0x12e
wmplayer.exe!_PlayerEntry+0x747
KERNEL32.DLL!BaseThreadInitThunk+0x14
ntdll.dll!RtlUserThreadStart+0x21

If I would have to guess I would say that it's the 0x0000000000000000 address in the first stack that is preventing Process Explorer from going further down the 32-bit part, but I'm not 100% sure of that. How can I make Process Explorer show the 32-bit stack for 32-bit processes?

Some more info about my setup:

Windows 10 version 1803 build 17134.556
Windows SDK 10.0.17763.132 installed
Process Explorer version 16.22
Symbol configuration:
Dbghelp.dll path: C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\dbghelp.dll
Symbols path: symsrv*symsrv.dll*C:\LocalSymbols*http://msdl.microsoft.com/download/symbols

Update: when viewing call stacks of 32-bit processes with Process Hacker instead of Process Explorer, the expected, 32-bit stacks are shown. For the main thread of 32-bit wmplayer.exe, Process Hacker displays:

0, wow64win.dll!NtUserGetMessage+0x14
1, wow64win.dll!whNtUserGetMessage+0x30
2, wow64.dll!Wow64SystemServiceEx+0x153
3, wow64cpu.dll!ServiceNoTurbo+0xb
4, wow64cpu.dll!BTCpuSimulate+0x9
5, wow64.dll!RunCpuSimulation+0xa
6, wow64.dll!Wow64LdrpInitialize+0x120
7, ntdll.dll!LdrpInitializeProcess+0x1887
8, ntdll.dll!_LdrpInitialize+0x4aa45
9, ntdll.dll!LdrpInitialize+0x3b
10, ntdll.dll!LdrInitializeThunk+0xe
11, win32u.dll!NtUserGetMessage+0xc
12, user32.dll!GetMessageW+0x30
13, wmp.dll!DllGetClassObject+0x1bf48 (No unwind info)
14, wmp.dll!DllGetClassObject+0x1bccb (No unwind info)
15, wmp.dll!Ordinal3000+0x75 (No unwind info)
16, wmplayer.exe!_PlayerEntry+0x4ff
17, kernel32.dll!BaseThreadInitThunk+0x24
18, ntdll.dll!__RtlUserThreadStart+0x2f
19, ntdll.dll!_RtlUserThreadStart+0x1b

Update 2: the problem only manifests itself with the 64-bit Process Explorer (procexp64.exe). When forcing Process Explorer to run in 32-bit, it shows the 32-bit stack:

0x00000000
win32u.dll!NtUserGetMessage+0xc
USER32.dll!GetMessageW+0x30
wmp.dll!DllGetClassObject+0x1bf48
wmp.dll!DllGetClassObject+0x1bccb
wmp.dll!Ordinal3000+0x75
wmplayer.exe!_PlayerEntry+0x4ff
KERNEL32.DLL!BaseThreadInitThunk+0x24
ntdll.dll!__RtlUserThreadStart+0x2f
ntdll.dll!_RtlUserThreadStart+0x1b

Update 3: in the meantime I've been able to confirm that the same issue occurs on a clean install of Windows 10 x64. That rules out a conflict with an existing driver or software on my system, and makes the theory of this being a bug in Process Explorer more and more likely. However, there doesn't appear to be any sign that this is going to get fixed anytime soon. Since I really need to be able to view 32-bit call stacks and Process Hacker still does this correctly, I see no other option but to stop using Process Explorer in favor of Process Hacker.