While exploring the new Tower area, my endurance reached zero, so I decided to use a potion (I had collected 10 of them at that point). However, the screen flashed shortly and it still showed 0 endurance.
Thinking it was just a display bug (the game's riddled with those) I left the tower and re-entered. Still 0 endurance. I then went to my inventory and checked the number of potions: 9.
So, the potion had been deducted but I had not gained anything from it.

I then went back to the tower and used another endurance potion. This time it showed 100/66. Going back to my inventory it now showed 8 potions.
So, some bug cheated me of the use of one of these rather rather rare and expensive potions.

Naturally, Kabam denies something like this could ever happen because their code is error-free (hahahaha!) and basically accesd me of being either delusional or lying.

So, did this happen to anyone else?