Scarabs dissapear form map device

I had my scarab build in map device, swaped to other character opened a black barya, did it, and whe i swaped to th character who have the scarabs in the map devive, they all gone

When you put in a Black Barya (or any other boss map fragment), all scarabs in the map device will go to your inventory. It has happened to me a few times where I thought my scarabs were gone, but I had just accidentally put them in my stash together with the boss loot, because I didn't notice they were transferred to my inventory automatically.

So check your scarab tab to see if you accidentally stored them.