Yes, I leave my pc(s) running 24/7, except in instances of long absence or bad weather.
It only manifests after several days of uptime and is solved by a reboot - but to reboot it forces me to physically shut the pc off.
I had thought perhaps hardware error (hence memory/system tests), but they're all clear, and it is only XIV that is hanging/affected... so I'm unsure.
The pc continues to work fine for other games/functions w/o issue, apart from hanging on shutdown. To clarify, it will only hang on shutdown/restart after such a hang in XIV - there is no issue booting though. I realize XIV may not be the root cause of it but I have nothing else to go on, so was hoping for some sort of diagnostic guidance beyond "run ccleaner + reinstall" I guess, but if that's all there is it can't be helped.

I get the occasional DX11 stack crash as well, but that's been ongoing since the start and has persisted through 3 pcs / numerous drivers, so it is not terribly offputting. I just don't get why it's hanging all of a sudden. I guess I'll try reinstalling if it occurs again.