Not always but after consuming some Artifact tokens this error message occurs and will not go away without a reloadui.

Message: Interface\AddOns\MiniLoot\core.lua:422: attempt to perform arithmetic on field '?' (a nil value)
Time: 07/10/16 10:33:09
Count: 1
Stack: [C]: ?
Interface\AddOns\MiniLoot\core.lua:422: in function `Tick'
Interface\AddOns\MiniLoot\core.lua:686: in function <Interface\AddOns\MiniLoot\core.lua:680>

Locals:

Sorry for the slow reply. I need to turn on e-mail notifications. I tracked down the error. Seems that the numbers use locale thousands separator and I had forgotten to account for those cases. The latest release should have that fixed.