In a log submitted in issue #143, I found a diffferent issue. The mod "Guarding" overwrites a method that we overwrite as well, causing a conflict.

Method overwrite conflict for method_7837 in guarding.mixins.json:ShieldItemMixin from mod guarding, previously written by com.github.crimsondawn45.fabricshieldlib.mixin.ShieldItemMixin. Skipping method.

I've already messaged the mod creator about this.

after an update, Guarding no longer uses our lib and the problematic mixin has been fixed, so I'm closing this issue.