no, I don't tried create/drop login because now the problem is solved
I do not know how, I just deleted and created some other logins and it seems that synchronization is done!
I am speculating because none of this seems to be documented, but adding any
new Login may have prompted SQL Server to re-resolve group-member SIDs to names the next time they are used so you may have indirectly and inadvertently solved the problem by adding a new Login.
but I want to find a solution for the next time :-)
If you happen to isolate it, please post back. I, am I'm sure others as well, could benefit from the information.
__________________________________________________________________________________________________There are no special teachers of virtue, because virtue is taught by the whole community. --Plato