I think I jumped the gun a little bit. Sorry about that. Had some time finally to investigate more and its not so clear cut.
So skipping _ UIBackgroundModes = {“audio”} _ still enables background music from other apps for me.
have you tried putting this
[lua]require(‘audio’)
if audio.supportsSessionProperty then
audio.setSessionProperty(audio.MixMode, audio.AmbientMixMode)
end [/lua]
At the very top of main.lua? I did a quick test without the buildSettings UIBackgroundModes and it works.