Hi,
As in the title I’m getting “Error please use the ‘Check Database’ function and sync again. If the problem persists please perform full scan” error when syncing. “Check database” function does not help at all, performing full sync helps and I can sync normally but only for short time - the problem keeps coming back after several successful syncs.
Please go into the preferences>Review>Scheduling section, and enable the v3 scheduler. Does that help?