Bug: I can not get my pantheon buff from Mephod, despite killing him and capturing his soul.

As title

I've captured the boss using a divine vessel, and handed it in to Sin. I have not received the buff (because I can still die to burning ground - so its not just a display bug). I can't re-do the map because it tells me that I've already captured his soul. (and no - the completed vessel is not in my stash) Please help

https://imgur.com/a/yOlRDqT

Are you perhaps dying to the burning tar that isn't classified as burning ground so still affects you even with the pantheon bonus?

Pretty sure its burning ground. unless the following mods are actually just misrepresented in the game and are actually burning tar.

the map mod:

Map has patches of burning ground

the eldrich altar mod:

Mobs drop burning ground for 3 seconds after death