So I figured I would re-install Message+ and confirm it was still an issue since I have had it uninstalled for a while now.
My findings:
As soon as the app is configured I started getting the audio issue (had spotify playing).... I force closed the app and fixed the audio by triggering assistant, then as soon as I reopened message+ I had the audio issue right away. It was reproducible everytime so I started adjusting a few things that may make a difference. Seems only way to get around this is to cripple its ability to run in the background, but it has some manual work that needs to be repeated between uses.
This is a work around for people that would use message+, just as a mms secondary for better pic quality.
If you install and setup message+ app then force close it, then revert permissions for sms /contacts /phone...you can have the app installed and configured without it causing audio issues. The downside is that when you open again you will be prompted to fix permissions to allow the app to work again. So you basically need to rinse and repeat everytime you need to use it. Basically I use standard message app with chat support and when I get an mms that's **** quality that I actually want better version of, I just open message+ to download it.
So far I have tested this for a day without issue.
Also FYI for people that may hit the first setup bug, it sends you a QR to scan to authorize the use of the app on this device with your number, so you will need to get that Pic on another screen (I used your phone app on pc) to scan with your duo.

