When dealing with the blind beholder in the Cult quest, I put the rift device (combined) in the quick item slot. How come after 1 use it disappeared?

Then I was forced to use the cheat to create another rift device for the 'diseased one' to complete the quest.

Did you check carefully in your carrying inventory after using it? Because after one use, the rod normally disappears from your quick slot and reappears in a character's carrying inventory. I remember wondering where the hell it had gone the first time.

If you've already checked that carefully, then don't mind the silly advice, natch. (-:

If your inventory was full when you used it then the rift device is lost. Same with figurines.