So I just ran a coaching workout, and on that workout I achieved a new 10K running PR. But for some reason the garmin web app didn't update my PR's. I've got my runs to automatically upload to Strava, and there the PR is updated. Then I tried to manually set the run as a new PR in the garmin web app, but this set the new time to the total time of that run, not the fastest time for the 10k. (The run was 10.8~ km with a time of 1:04:13, the 10k PR should be 0:57:02, but it's set to 1:04:13)
But now when I try to set the record back to the previous PR run it also just updates to the total time of the run.
So in short, I think there is something wrong with the manual PR updating system.