Guild Window members offline since wrong
 

I was going to do our minthly guild clean up today if members who have been offline for over 30 days

It showed everyone who as not online now as being offline for at lease 28days i cjeched with one of the other officers who uses defult UI and they was showing as correct time offline
discount this swapped to another toon it was fine swapped back to main and everything was ok odd though

I just checked mine and it was working properly. Check again next time you're on and report back.

That data is streamed from the server, Fetish or any UI wouldn't have anything to do with it.