My personal records (swim) do not update. I don't get the buttons to approve. I use version 4.49.2 on my iPhone. Neither it is possible to approve in the web interface, it doesn't appear.
Which Garmin watch do you use? They don't all support swimming PRs.
Garmin Connect: Personal Records for Pool Swimming Activities | Garmin Support
I don't see it listed, at least not in the list provided by Garmin's link above.
Which Watches are Compatible with Swim PRs?