I received your data and I am not having any luck duplicating any issues. As most of the recent changes that could impact volume were all done with checks for Bluetooth, you're really not hitting any new code. Also, none of those code changes were done in the time period between June 6 and 13. Most were done in April and late May. I suspect you may just be dealing with some Apple music playback issues. That would also explain the button issues.
Can you confirm that all issues are occurring with the old iPad and not the newer one?
Can you confirm that all issues are occurring with the old iPad and not the newer one?