If you mean that you cannot upload new workouts from Garmin Connect to the device, then connect the device with a USB cable to a computer, delete unneeded workouts from the folder //GARMIN/Workouts, and then use the button Send to Device in Garmin Connect at the concerned Workout again. There seem to be a limit, and the watch can hold only certain number of workout files, so old ones need to be removed to make place for new ones. Why it does not happen automatically, is another question, but that one you have to ask to Garmin, not here on the user forum.
In that case, try (re)scheduling one of the workouts, and Sending to the device again. Open Garmin Express when sending to the device over USB, and watch for errors.
I have similar issue with my Forerunner 645 Music. From the Garmin App, the selected workouts were sent to the device. I also connected the device to my laptop via USB cable and confirmed they're listed in the workout folder. Still they won't show them on the watch. I deleted them from the folder and installed it from Garmin Express, which showed no error in the process and they're listed once again in the workout folder afterward. It seems an issue with the user interface, that it won't show the "My Workout" under Training. How can this be fixed?
You simply have to look for the workout from the activity of the exactly same type as you selected when creating the workout. If you created a Running workout, it will be listed in the Run activity profile. If it was of the type Strength, then it will be available for Strength activities, etc.
