Like in title quest bug. There is 100 quest items to collect, I had almost full quest done, but had to make relog, and after that all items gone, had to start quest again.
i never had problem like this, did you try to kill a few mobs to see in the notification that it is already gone?
because as far as i remember on this quest you dont ge tany quest item in Quest inventory, just the game remembers which and how many you have
open the Quest tab find the relative quest and click the notification button once or twice to see if it is showing 0/20 to all or the progress you had before the relogin
if they are indeed gone nvm then just farm them again its xp anyways