Reference topics: (in descending chronological order)
NPCKitpack borking with EE KIT.IDS
Refinements borking any KIT.IDS (already BWPFixpack'd)
Aurora borking ToBEx'd KIT.IDS (already BWPFixpack'd)
So yeah, stuff seems to be breaking because everyone and their mother uses the BG2Fixpack's extremely destructive block for their own KIT.IDS patching: (which I'll point out is not BG2Fixpack's fault because you're EXPECTED to install it before anything else)
Line 336 in setup-bg2fixpack.tp2 (from BG2Fixpack v10)
Why this be bad you ask?
1) Lines like this: (like the Imp pointed out in the NPCKitpack thread)
REPLACE_TEXTUALLY ~.*\bBLADE\b~ ~0x400D BLADE~
will fix kits containing the word blade, which includes the vanilla Blade as well as the Blademaster, Bladesinger, Bladesinmapants, Shadowblade, Yomommasblade etc.
2) Older mods (like NPCkitpack & aurora threads linked above) do not take into account that ToBEx unlocks the secondary byte for kits (so you can have long ass kit IDs like 0x40000000 instead of just 0x4000) - this has been currently handled in most mods by the BWPFixpack
So what do we do?
We improvise
Give me a vanilla non-modded KIT.IDS from BG2ToB, BGEE & BG2EE, we'll do a swift comparison and make the BG2Fixpack block affect only vanilla BG2ToB IDs while making it compatible with the EEs.
TL;DR : Someone please donate a vanilla non-modded KIT.IDS from BG2:ToB (non-EE), BGEE & BG2EE