After clicking on ‘restore delete’ on the list page, there will be an error message and no prompt as follows.
tips:Internal server error, trace ee470ae7
Unfortunately Garmin has recently disabled historical data fetch for all authenticated users. You need to disconnect from Garmin and then re-connect, ticking the “Historical data” toggle. Then the undelete might work.
If that fails then you need to download the files from Garmin Connect and upload using the “Upload” button on the calendar page or use the “Import All Garmin Data” button in the Garmin box in /settings/connections.
Okay, I’ll try next time 