It seems that there were changes brought about by the required compiling of the app against API 31 that caused it to crash for those using it on Android 11 or Android 12 (earlier builds of Android were unaffected).
One of the changes is a tightening of security surround the permission to access the entire file system on the phone. I was using that previously to put the various GPX, KML, and SUM files in a convenient location. In order to continue doing this, I would have needed to request an exception, which quite frankly I can't justify. There is NO REASON to gain full access to the file system to make these files publicly assessible, but they MUST go in a folder set aside by the operating system for Bike Tracker specifically. You'll now find the GPX, KML, SUM, RWG, and TCX folders in:
/Android/data/com.pcability.biketracker/files
Since the new app can't access your previous files, I can't automatically copy them over for you, but you can copy them there yourself using your PC or a File Explorer app (the latter having full file system access).
With any luck, this new build should be available later today, pending approval by Google.