I have not seen this. A couple things to check out would be the error message - do you get any indication of why the sync fails? If not, then I would check the ArcGIS Server logs and see if you can get any hints from that. Otherwise, I suggest you log a support case to try and reproduce the issue with them. They should be able to assist you in troubleshooting, and if they can reproduce the issue, they can get a bug logged with us to fix.
Thanks,
Luke
