Hey @rayray, 

This post has been escalated to our Support team. If you have a similar question please submit a support ticket and we will investigate further.

Is there any update on this? Even I’m facing same issue and 88 synced activities and I don’t want to lose those

Hey @Sharathnasa, 
In this case, can you please force quit both the Strava watch app and the app on your mobile device?

To force quit the Strava app on your watch, press and hold the side button until the shutdown screen appears, and then press and hold the digital crown until the app closes. You must be in the app to force it to close.
 
I hope this information helps point you towards successful uploads.

I am having the same issue it started yesterday so have 1 unsynched activity on my apple watch and have tried what you suggested above but it hasn't helped. I have also tried powering down both my match and iphone and restarting and that hasn't helped either. I tried doing a small second activity to see if it would force it through but it just came up 2 unsynched activities. I just had a new pb on the run so had wanted to upload the activity so am reluctant to delete it?