[solved]
During my Park Run this morning, my Garmin Epix Pro froze when I stopped the run.
I restarted the watch and it immediately came to the end of activity menu and allowed to save my run.
Unfortunately the activity will not upload to Garmin Connect and the usual fixes have all failed.
I've also tried the tools at FitFileTools.com but this has also failed to fix the file.
Any ideas?