I see an announcement of the release of a non-beta 8.5 Build 6001qm here:
viewtopic.php?f=73&t=15798
I am running a beta of X1 8.5.2 6001si. It would seem that the non-beta released today would be the latest (and would avoid any beta expiration. But the link in the thread above will not install. It thinks my beta is a newer version (which it should not be). What should I do?