We are an org running Exchange Hybrid (current CU) with all of our mailboxes in the cloud. We also used to have Lync & ADFS installed on premises about 3 years ago, but decommissioned both. We have a user who recently had their UPN changed. They were email@example.com for about 6 years, then were recently shortened to just firstname.lastname@example.org. When I updated their UPN in AD I dug through attribute editor and replaced any mention of JohnS with John. This includes the SMTP and SIP attributes under proxyaddress. Email and pretty much everything else works fine for them, *but presence in Teams has been pretty thoroughly borked since the switch.* About 90% of the time all of their contacts appear with the white circle 'status unknown', and the appear to their contacts as the same. We've tested on multiple connections, devices, and locations and can't seem to correlate anything with when it breaks.
I've opened a ticket with MSFT support. I want to pick the brain of the mindtrust though, what attributes / reg key settings / cached objects help presence with MS Teams? There's a breadth of documentation on how to troubleshoot presence for Skype for Business, but I can't find anything similar for Teams. Any place I should be checking on this user's devices or in AD/AAD?
Does this happen if they sign into Teams on another device? If not it could just be something stuck in the cache. You can wipe out the cache by first completely exiting the Teams client, then delete (or move if you prefer) everything in %userprofile%\Appdata\Roaming\Microsoft\Teams , then start Teams back up.