Hello, as of Ember's Construct 1.3.5, several materials no longer have stamping recipes. Some still do work (broad axe head for example), but most stamps do not.
One that works:

One that does not work:

Huh, that is weird, I will take a look.

Fixed with 4dec5f4. The problem was in a method NBT data wasn't compared and therefore all recipes with the same inputs (without nbt aka any stamp) & fluid with different output got discarded (besides the first one).

I will see if I get a hotfix out or fix #20 beforehand, we will see