If activities can't be transferred successfully, pls try to reauthorize the account again. 

You may refer to the article to reauthorize strava account.

If the problem persists, pls try to connect with iGPSPORT customer service for more information.

NOTE:

Only the activities after the binding can be automatically transfered.

The data before the account is bond can't be synced automatically, you need to upload them manually.