Zwift Ride - Was a PR but doesnt show up in the records page?

I did the TdZ Zwift Ride a couple of days ago, and it was a PR for average speed by a long way. However, Garmin hasn't updated the records page to reflect this 40km record, and I remember it didn't do it before either when I did a 40km PR. 

When I go to edit the activity and set as PR manually, the "Set as PR" option in the dropdown is blanked out..anyone know why this is and what can be done to sort it?

Thanks in advance,