Locked out of Cruel Act 3 Slithering Dead Quest - Reference 209500115

I was going back and redoing all of the quests I missed after completing the campaign and wanted to get +10% chaos resistance from the Cruel version of the Slithering Dead, but it looks like the quest completed without me ever getting a reward from it. The quest no longer shows up in my objectives and finding the corpse in the Venom Crypts does not drop the venom quest item to turn in.

The quest does show as completed in my quests list, but the bug report screenshot shows my world screen and has the relevant icon with a highlighted potion but no text about a reward, so it doesn't seem to be an issue of me doing the quest and forgetting about it later.

Same exact issue for me says completed but never got the vial

I have the same thing :

- I have finshed a3 cruel but left some sidequests for later
- After finishing a3 cruel I partied with a friend and cleared one endgame map
- We tried to do the slithering dead quest
- we cleared the venom crypts, clicked on the body but nothing happened