Intermittently, audio redirection fails for users in a hosted-shared desktop ICA connection

Problem Cause

•    A user configured with Client Audio Redirection enabled launched the same shared desktop from the same receiver multiple times via Logon/Logoff. 
•    Whenever an ICA session is launched via Logon/Logoff each time a different session will be used, also the GroupPolicy_CseClient invokes a process on the VDA to create/update the group policies pertaining to the logging on session.
•    Also, the Citrix Audio Service starts initializing the Audio Virtual Channel (VC) and invokes another process to check if the AD settings are up to date for the session -

If Not up to date? (in this case, the reported user session with disabled audio) -

It starts a PolicyTimer and RegisterWaitForRegistry based on the configuration in the registry path:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\ica-tcp\AudioConfig\PolicyTimeout (DWORD)

..and waits for the timeout value for any registry updates of the audio related group policies for the logging on session. The default timeout value is 4000(ms) which is also the value in this environment and the timeout expired with no registry updates for the session invoked during the interval, and the AD settings related to audio for the session were read eventually.

The 'Group Policy processing by session ID' invocation happened after the Audio VC was initialized using the audio AD settings read for the session and hence the stale AllowAudioRedirection registry setting value which happened to be "0" in this case was used instead thus disabling the audio. If the stale value was "1" the audio would be enabled even without the Group Policy update processing taking place before the Audio VC initialization

If Up to date?

The audio VC is correctly initialized with the correct AllowAudioRedirection policy value for the logging on user session.