Azure Virtual Desktop - Black Screens on logins - What we've tried so far

Is anyone dealing with Windows 11?   We have black screen issues with Windows 11.  Have been working with MS Support for 3 weeks now and support gets worse every day it seems.   Every new engineer we get assigned acts like its a new case, doesnt see anything else that was done and doesnt know what logs / dumps we have provided.

So far, we have given the following and still we have no answer and they want more logs

- LiveDump

- Complete Memory Dump

- Explorer / SIHOST process Dumps

- Full ProcMon Boot Logging Trace

- TSS Logs

- CM Diag Logs

- WPR Trace

Yet a new engineer comes on every time seemingly wanting more logs.  When we ask what the deal is with the logs we gave, we dont get straight answers.   Angry does not convey how we feel right now.  Their support could not possibly be any worse at this point and I'm fed up with it.  Even our Tech Account Manager tells us they are gonna do something for us, then doesnt.  When questioned they say they are getting the new engineer up to speed, then we dont heart from them for 4 more hours.  Its a joke.

Anyway, first we were told 

thread is waiting for Host Activity Manager (HAM) to Terminate a snapshot of all hosts in the specified package(Here is only one application package in the queue). Following are the details about the package.
In all cases we worked so far, the application to which HAM is waiting on is Microsoft.AAD.BrokerPlugin.
0: kd> !mex.t ffffcc0573383080
Process Thread CID UserTime KernelTime ContextSwitches Wait Reason Time State
svchost.exe (DcomLaunch) (ffffcc05654170c0) ffffcc0573383080 5b8.9c18 188ms 359ms 4600 WrAlertByThreadId 3m:56.156 Waiting

Hence it is not clear as what happened to the worker thread. To understand that we need more details.
1. Process dump of sihost.exe from the affected session.
2. Process dump of explorer.exe from the affected session.

We are tracking this issue in a Bug record internally. Application event log has following errors logged (this is consistent on all environments where this issue was observed)

Events ID 10 is present where the same issue is observed. Looks like this event is related to the black screen issue the users are experiencing. We are investigating this further.

We provided more dumps and a COMPLETE memory dump only to be told then from the dump that out issue was

explorer isnt loading as its trying to load the shell process but cannot as all CPUs are tied up with other processes.

So they are completely ignoring, or just never even seeing the previous notes about the worker processes and AAD BrokerPlugin as the issue. Or they have no clue and are just stringing us along until they have something valid.

We are getting no where with this and the support level we are getting is pathetic.