Hello Obsidian team,
the bug I encountered is as follows:
After leaving the cave at the start of the game, I looted Heodan's body and put the Potion of Minor Regeneration I found on him in my quick item slot. I then saved. When reloading said save, the potion is gone from the quick items and is nowhere else to be found either. This is reproducible and occurs both with quicksaves/-loads as well as manual ones.
Here is a linked zip file file with a save where I haven't looted his body yet and one that I made after looting and putting the potion into the quick item slot. That second save obviously will have the potion missing. It also includes the output log file as well as DXDiag.
I hope the information is sufficient and that you can find as well as fix the bug.
Thank you for an amazing game.