The Enable Base Submix toggle is ignored in the MetaSounds graph.
If the sound is added to a level, it behaves as expected.
The Enable Submix Sends toggle works as expected.
1) Launch AudioQA
2) Open the MSS_Test_WavePlayer asset
3) Click Source at the top of the graph to open the Source menu
4) Set the Base Submix to QATestSubmixSingleFX
5) Play the MetaSound. Counting with a long r.everb effect plays
6) Uncheck the "Enable Base Submix* toggle
7) Play the MetaSound again
Expected Result:
No sound is audible as the base submix is disabled
Actual Result:
Sound still plays with the effect
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-147819 in the post.