https://bugs.winehq.org/show_bug.cgi?id=48734
--- Comment #1 from Zebediah Figura z.figura12@gmail.com --- It's broken because quartz.dll gets unloaded and reloaded at a different address. We need to both properly unregister the class on DLL unload, and properly implement DLL refcounting so that we don't unload quartz.dll while things are using it.
I doubt the linked commit is really a regression; it just probably works sort-of-by-chance sometimes.