I used Poweramp with the same car and it worked well, until some update that messed things. Downgrading t build 828 was a workaround, but only for some time. It finally crashed and I was forced to update.
Before requesting support, I tried a lot settings in the phone and in the app, none of them worked. I also contacted with the app support via email with all the details, and they gave me only the standard reply about re-installing the last build.
I attached my question to this thread because it was similar to others. For instance, forlau's message describes exactly the same issue, but my car is Toyota instead BMW and my phone is another Redmi series. I don't think this is related to one specific car audio, but perhaps a integration issue with the latest MIUI versions. I'm really tired of this and now I'm using another app that works fine.