All my Cardio and Strength activities are visible in my calendar after syncing my watch to my Garmin Connect app but my runs no longer show even though I can see the saved run on my watch.
toej, a few possibilities:
You've logged in with a different Garmin account - Data is Missing from My Garmin Account After Syncing
You have corrupt activity (.fit) files on your watch that can't sync with Garmin Connect - In this case try a manual upload to Garmin Connect Web to see if they are corrupt - How Do I Manually Upload an Activity I Recorded to Garmin Connect?
If you get any message other than Import Complete, then there is a problem with the file. In that case, zip the fit file then attach it to this thread. We can take a look to see if it is repairable
Zip the file, then in a reply post Insert >> Image/video/file >> Upload >> browse for file >> OK.