After two rounds the next round does not appear in the activity logs. The scorecard and shots are visible in the golf app. So that's repaired. Restarting the S70 after two rounds does the trick.
It has been ten months since the problem started after a software update, yet there is still no permanent solution. I'm using the latest versions of the golf app and Connect, and the watch is configured correctly.
Garmin, please fix th issue.