This problem drives me nuts!
I did a benchmark run and it appears in My Day, but does not want to sync with the Garmin Coach Plan. Tried already all things that I could find on the internet: change the status, Connect with a cable to the Garmin Windows Software, reschudeled the training and synced it, …
Driving me crazy! This seems a problem that is ongoing for years and Garmin still didn’t solve this. Crazy!