As you can see in the photos below, the center item requires a silver ingot from the Thermal Series mods, when it should be requiring the ingot from this mod. Simple oversight that I would try to fix myself, if I knew where the code for it was.

Mod version 2.7 for Minecraft 1.18.2

There showing `Accepts any forge:ingots/silver'. So you can use Thermal's Silver ingot too.

What I'm saying is the center slot isn't accepting any silver ingot

The reason why the middle slot only accepts only Thermal's silver ingot is to avoid recipe conflict.
And it came from Thermal. https://github.com/CoFH/ThermalFoundation/blob/1.18.2/src/main/generated/data/thermal/recipes/storage/silver_block.json