Hi, I have noticed a problem with watch / phone sync recently, with the latest version of Garmin Connect - 4.36.3 - not sure about previous .36 version but this one was causing troubles for sure.
Today I was not able to sync the watch with phone, both showed no connection. After several restarting of both devices, removing connection and re-pairing again I was able to restore the sync and notification about incoming call. However, even with all the notification options allowed in phone and watch, i was not able to get any message notifications at all (FB Messenger, MS Teams, WhatsApp, sms).
Solved with downgrade to Garmin Connect version 4.35.1
Older versions can be downloaded here - https://www.apkmirror.com/apk/garmin/garmin-connect-mobile/garmin-connect-mobile-4-35-1-release/
Don't have any other Garmin watch to check, so it could be an issue with backward compatibility of Forerunner 35, but i have noticed there is plenty of similar issues mentioned in recent Google play reviews for other watch types too.
Would be great if this could be investigated and fixed, I'm really happy with the app upgrades and would like to continue using it :)