With Microsoft cloud services dropping a lot lately, there is the possibility that user sessions can be terminated in an unclean manner, leaving a session file handler still active. In this scenario, the user cannot log back into the session, because of the hung file handler. Rebooting the VM will clear the hung handler, using a web interface to single out a specific user and disconnecting the file handler may also work. A preventative measure you can take to just reduce the chance of hung file handlers is add this to your WVD VMs.
reg add “HKLM\Software\fslogix\apps” /v CleanupInvalidSessions /t REG_DWORD /d 1 /f /reg:64
Notes
https://docs.microsoft.com/en-us/fslogix/profile-container-configuration-reference
Disconnect File Handler in Nerdio
NEW METHOD
STORAGE > Azure Files > Manage > File handles > Select Name > Click ‘Close File’ button
OLD METHOD
SETTINGS > Integrations > Azure Files > Click Lock > Enter Name > Select Name > Click ‘Close File’ button