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LucaBerniniKT Borked on us too after Windows Updates were installed this afternoon. Get-RdsSessionHost indicates the last heartbeat was received right before the VM was rebooted to install updates. KB4512508 is the culprit - I uninstalled it but the agent was still messed up. Dropped the Session Host from the host pool, uninstalled all the Remote Desktop agent stuff, followed the instructions for registering a session host to an existing pool via powershell, and got it working again after a reboot. Going to pause updates for a bit until a new agent comes out.