Restarting PC and Factorio (obviously) did not work.
Multiple restarts of Factorio did not work.
Disabling mod, loading world (which deletes all mod entities), re-enabling mod, and loading back in DID work, but is likely not going to be a good solution
In this world, conversion and unconversion tool are working properly and reporting correct numbers back
Unsure if intentional, but picked up Belt Quality belts convert back to vanilla quality belts. This was the case in the bugged world as well
Reloading into an unchanged world with bug did not work, even after disabling.
Conversion Toggle button is not having a difference, nor is it properly converting belts in my inventory when the inventory is updated
Edit: Loading back into working world after a while of messing around in non-working, working world is no longer converting.