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

GlenW1530 we have had this issue for weeks, started with black screens, fixed that with the KIR and then 80% of users getting Office 365 auth issues and no access to outlook etc. The only thing that helped us was going from 16 users per host to 8 per host with 1 cpu per user i.e 8 core machine for 8 users. Someone else mentioned it here and it seems over 10 users appx starts to fail and cause this issue. We also disproved anything to do with fslogix as this happens even when excluded from fslogix.

Also autostart all vm's before users come online to ensure they are "warmed up", spread the logins with "Breadth First", and look out for the AADbroker failing in event viewer as if this breaks, it breaks for all users on the host.