The basic shield tier for gobber is missing the required ingot for it's recipe:

I understand this may be outdatted version for this mod, but i hope it might be fixed, currently just OP shields from only 6 planks.

There are a number of fixes in the newer versions that I will be backporting soon. So hopefully this issue will be resolved

I'm dropping support for versions of the mod prior to 2.0, but I'll make sure this isn't an issue in 2.0+