4 scarabs in 5-way map device - only 3 get used (standard)

Bug report 1,239,850,124

Character: Furyangel_Caustic on Standard

I have a 5-way map device unlocked back in Legion league. When placing a map within centre of device and 4 scarabs around the outside, only 3 scarabs get used. On returning to hideout a scarab is still sat in the device. The position seems random (either of bottom slots so far) and the scarab type is also random, tried a few combinations.

I did the 4-way legion fight again in order to re-unlock the 5th slot in case it had reset somehow but it is still happening since then.

Update: Seems to always use one less. Tried to run a map with 3 scarabs and only 2 got used. There is always one left over in the map device once back in hideout.