If you type /who or even shift click a players name in chat to see their level, it breaks the ability to use these commands. It seems to fix itself after like 10 seconds but it’s annoying as hell not being to look at players when trying to form groups.
“/Who” is throttled on purpose (ten seconds, or thereabouts) to prevent you from flooding the server with /who requests.
That being said, inspecting someone isn’t throttled, nor is anything associated with shift-clicking their name. If you’re having problems with that, then try a full UI reset; only the /who command has a delay attached to it before you can “/who” again - you should be able to inspect or shift-click names all day one after the other.
I have the same problem (and all my friends as well, talking about classic tbc) when for example I put 55 to see the players connected of that level, they show instant, but if after I put 56 it doesn’t work until 1 minute has passed, then it shows players lvl 56. This is very annoying because I use this tool to make groups for dungeons and it makes it so inefficient. This problem starting to happen 4 days ago, before dark portal was open it was working perfectly fine. I hope it gets hotfixed soon.