Information

Minecraft version: 1.18.1
Modloader: Fabric
Fabric loader version: 0.12.12
Environment: Single & Multiplayer

Mod name: Fixed Anvil Repair Cost
Mod version: 1.6

Description

Anvil does not repair durability on items while Fixed Anvil Repair Cost is installed.

I see the same issue. If I set the repairCostLevelAmount = 0, then I am unable to repair the durability of the item

Minecraft version: 1.18.1
Modloader: Forge
Forge loader version: 39.0.5
Environment: Single & Multiplayer

Mod name: Fixed Anvil Repair Cost
Mod version: 1.18.1_1.7
Collective version: 1.18.1_3.8

Just to clarify, my example is with the default settings so attempting to repair the gold boots in my example image would consume gold ingots and exp levels and receive zero durability improvement in return.