So, while doing an earlier quest with Kithyaei (? name), I got this side quest. I found the box and cleric's journal.
I don't recall if I received the Antique Holy Symbol required to continue Apostasy Search the Monastery and it wasn't flagged quest item, or if it was never present.
I have checked every merchant I can recall having interacted with, and most of them have retained items I've sold them - but the Antique Holy Symbol isn't in their sellable inventory.
This leads me to thing 1 of 2 things happened:
1. I accidentally sold it to the Caravan you find in the wilds that launches the encounter with assassins or spies. I never encountered that merchant again, and it's the only one I can't check.
2. It was never present in the container with the small box and the cleric's journal near the graveyard & Mausoleum where you free K.
Ideas, suggestions? Does this game have any console functionality, either to place an item in a container or PC inventory? Or a live DM capability (similar to what existed in NWN1)? That would give me ability to fix. I am reluctant to report as a bug bc I can't recall 100% certain whether it was present or not. Ability to export chars from a save (and re-import) would at least allow me to (*not for cheating*) to export char, bring them into a small dungeon with 1 chest containing the missing item, save the char, re-import into campaign and voila can close this dumb quest. Ability to advance quest by stages using console commands (similar to Elder Scrolls series singleplayer) would be useful. I currently do not play this game in multiplayer.
The closest game save where I might have had it is over 10 days old. That's 10 days with multiple quests, a few hours per day (weekdays) and more on weekends. Argh!