This is commonly caused by using the old method of accessing the global GameTooltip as opposed to the new tooltip processor calls.

hmm but I am actually using the new methods

But you're using GameTooltip instead of tooltip in https://github.com/derfloh205/CraftSim/blob/1654d38f10fadd3a22400d1a40819384b03a61ba/Util/Tooltip.lua

Ah now I see, thank you for pointing that out
Will be fixed in 1.8.3+