I was pondering this and wonder if it has to do with the character data refresh. Did either of your friends have alts?

Ever seen when your HUD and everything gets seemingly erased? I know that happens with a write error on the windows/documents folder and that any actions you take cause your client to temporarily disassociate from the server while it rechecks and refreshes that folder (I've tested this with tracking how UI changes can get all wonky) from what I'd seen it seems most often to occur if you submerge your account (so you quit for a month and come back before the 45 days are up) and seems to be worse the larger your ../games/FF XIV ARR folder is; which can get pretty big given its the default screenshots and character profile folder.