This also occurs with Submix overrides and for settings where the listener is outside the volume.
Likely when this setup occurs, AGVs needs to know to re-evaluate interior spaces
1) Launch AudioQA
2) Add an Audio Gameplay Volume to the default level
3) Add a SubmixSendVolume component to the AudioGameplayVolume
4) Set the Listener Location State to Inside the Volume
5) Set the Sound Submix to QATestSubmixSingleFX (this submix has a long reverb effect on it)
6) Add any sound to the level (I suggest something eady to hear reverb on like an impulse or voice) and place i*t inside the AGV*
7) On the sound asset set the following:
9) Enter au.3dVisualizeEnabled 1 so you can see the sound
10) Move the camera into the AGV and observe the reverb on the sound when inside. The reverb stops when outside the volume
11) Move the camera outside the volume far enough that it becomes virtual (debug text turns blue)
12) Reenter the volume
The submix send is retriggered on entering
The submix send no longer works after the sound has become virtual.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-197019 in the post.