The USB in the glovebox is not for playing music, it's for transferring music to the hard drive and updating the maps.
Try playing music from a memory stick in the centre console USB and see how that goes, it could be an issue with a compatibility problem with the phone (maybe :? ).
I'll explain a couple of problems with your fault...
Potential AUX/USB socket fault - The AUX and USB are separate parts within the combined socket, hence no common parts for this fault.
Potential short wire (the 9" first connection) connection fault - If this was loose then you'd expect it to be faulty all the time and not allow you to play for a while then pack up, and then do the same next time.
Potential MULF/Combox fault - This is more likely as the bluetooth side will be a separate part of the internal PCB to the audio processing, so although you are getting your bluetooth through this may be the case. Now checking your car I see it's a 2011, so I'd assume it won't be a separate bluetooth module (TCU) and unless you have bluetooth music then it'll be a MULF (for bluetooth music streaming it would be a Combox). Now MULF's are cheaper to get hold of, and I believe a used unit "should" be plug-n-play as you already have all the correct coding there for it.
Working on that assumption, here is a relatively close dated version (cross referenced that it is suitable for the E89)..... https://www.ebay.co.uk/itm/265532462623?hash=item3dd2f7d61f:g:gAQAAOSwTdth~EUP
Now if it's not a MULF and you do have bluetooth music streaming then you'd need one of these instead, as you can see a bit more expensive (actually this one is very well priced)....
https://www.ebay.co.uk/itm/265532451106?epid=3025445313&hash=item3dd2f7a922:g

4EAAOSwT4dh~ELq
Obviously I'd suggest checking everything first before buying a replacement, but it gives you the idea as to how cheap MULF's are.