Hey Matt!Indeed I can reproduce this issue. This will be solved in MadMapper 4.0.6. Thanks for reporting.
The fact that audio stops when opacity is zero was introduced before we could link audio to surface opacity. The idea was that we could control a set of layers opacity with MIDI faders and so have the sound stopping when layer is fully off. I'm wondering if it still make sense now. I'll check with the team what is the best approach but I think if audio is not linked to opacity, it would make sense not to stop audio track.
the "Link to Opacity" function is still not working properly! Either it is enabled or not, Audio only will be played if the Opacity is not 0%. So the audio level always depends on the opacity level. Tested in all 4.0x versions with HAP.mov
Please fix that issue in the next version! We need the function disabled for our next show. Thnx