I'm having the same Wrapper x96 tank issue as above. Noticed I was using Mod Manager 2.6.21 so I tried the following tests:
KSP x86 w/MM 2.6.21 = Borked
KSP x86 w/MM 2.6.20 = Borked
KSP x64 w/MM 2.6.21 = Borked
KSP x64 w/MM 2.6.20 = Borked
all hanging up on path: WarpPlugin/Parts/FuelTank/WrapperTank/WrapperTank - x96/KspiWrapperTank96
BTW, thanks for all of your work on this great mod.