How to get Finality Auger catalyst? Got weapon drop after completing Drowning Labyrinth

[livid cave]

I had already finished drowning labyrinth quest before getting the exotic drop and can't get the catalyst now. Things I've tried:

1. Full dungeon run solo. Had entered the code correctly but lenses didn't spawn after 1st encounter. Only got focused gear from final chest, no catalyst.

2. Went with someone who was on last step of catalyst quest chain. He got the catalyst, I didn't.
3. Checked with Ikora, no quest. Quest archive is blank. So can't pick up the quest again.
4. Double-checked the weapon (someone suggested this). I don't have the catalyst yet.

Any ideas how to fix this as every youtube videos says quest completion gives the catalyst from vault.

[iron rune]

did you try entering the last code in at the start and doing a full run

that should open the door at the end and give you catty