Okay. I'm grasping here. Do you have any audio pipes setup on these MDs?
I could be way off, but here's my current working theory:
App Server only controls the volume when there are no audio pipes defined. If you define an audio pipe then app server will set a volume level on the analog card and pass volume commands to the device defined by the audio pipe. I can only speculate that app server may think it is not the audio controller and therefor setting an arbitrary value and ignoring the volume commands.
tchak? Does that sound plausible at all?
That also doesn't explain why this has happened after an upgrade, unless something got changed in the DB, hence my pipe questions... grasping.