Synchronization problem between Session and Capture One Live Album

Hi,

I am using Capture One Live to ask client to make their selection.
I send them the link of the capture album. They mark the pictures they like (with 5 stars) and it synchronises directly with the session album so I know which photot to edit.
Sometimes there is a problem. Some pictures dissapear from the Live album but are still in the session capture folder. 
Sometimes the amount of pictures marked with 5 stars does not match.

Am I doing something wrong? Is it a bug? Is there a way to fix it? 

Thanks.

Lillo