Multisport bpm missing for swim

Hi,

I just did an olympic distance race. After the race when I saved it, the watch was crashing and restarting.
After restart I could save it but however the bpm data from the heart strap is missing.

In Garmin Connect is now the file without the bpm information, when I was back home I have downloaded the information from the heart strap to the activity.
How can I delete the file in Garmin Connect and upload the updated file from the watch?