Minecraft 1.18.1
Fabric 0.12.12
Impaled 1.0.2

Following instructions on the Wiki, I'm trying to obtain "Sincere Loyalty" on tridents but this doesn't seem to be working. Tested in custom modpack and in a clean sandbox, same results.

Example images from modpack.

Don't know how helpful this might be, but here's my log from testing in a clean client. Same results as the modpack, couldn't upgrade any Loyalty III Trident to Loyalty IV.
https://mclo.gs/UNwQziw

You're trying to use an anvil, try doing the same thing with a smithing table instead!

Thank you!