In the Garmin Connect App -> go to your watch -> Connect IQ App -> Applications. It has to be listed there, either under "Installed" or "Not Installed".
I, as well as some others, had same issue with Golf app not showing or available to add.
Only Fix for now:
Settings/System/Restore Defaults....hit YES
It's a pain to redo all settings afterwards, add watch faces and Third Party apps, but only way I could get Golf app to show. I'm guessing this should bring back Strength Training App as well.
