Yup, Xur doesn't have the Xenology quest for any of my chars since I've abandoned it.

That might just be because you abandoned it. Try going to Xur on all three this week & see if it works.

I went to Xur with every single char the last two days. Also checked the quest archive on every one of them. There's nothing to get for me, just the standard exotics from xur. the first time i've abandoned the quest i was able to pick it up again on my warlock from xur but i needed it on my hunter so i abandoned it again. after that it was completely gone.

Did you go to Xur on each character before you deleted the quest?