Earlier today I tried to upload my run to my sports, it took ages and kept saying try again.
Eventually it synced to my watch and uploaded the run to my phone.
However, it didn’t sync to Strava. So me being an idiot thought that if I deleted it I could re upload it and it would sync to strava. But I’ve since found out it’s not on the watch after syncing.
The previous advice given on here is no longer valid as there is not an Apps tab on iTunes anymore!!