Anvil Tile (White March) Disappeared from Stash

[Grumpiest]

An anvil tile is a quest item required to enter Durgan's Battery in the White March.  It's obtained from the Ogre Matron.  It disappeared from my party's stash with the result that I can't complete the main quest.  I only recently discovered the tile had disappeared when I tried to enter Durgan's Battery. 

 

I loaded a save from the end of August and sure enough it's in the loot pile remaining after defeating the Ogre Matron.  I believe I was a victim of the disappearing item bug!

 

I've spent a LOT of time getting to where I am now in the game since that tile disappeared.  I've basically finished everything except dealing with the Alpine Dragon and of course Durgan's Battery.  I don't think I can face restarting the game from the beginning and repeating everything I've completed.

 

Is there any way I can move the anvil tile from the old save to my most recent save?