Went on forum and saw this from 2 years ago:
I have a similar issue. My Vivoactive 3 saves the round to the device, and Garmin Connect detects that I have an "activity" that captures the physical distance that I walked, but Garmin Connect does not detect that I have a round of golf scores to save to the Garmin Golf app.
My current workaround is to plug my Vivoactive 3 directly to my MacBook and sync via Garmin Express. Once I do that, Garmin Golf syncs to Garmin Express and I can see my scores in my iOS app. However, I would prefer to have Garmin Connect sync to Garmin Golf, which it used to do (until the ransomware attack at the end of July 2020).
Any ideas? Any support from Garmin on this issue?
Thank you.