[2021.3] Custom enchantment not showing up in the enchanting table

I am trying to create a custom enchantment, however I am not having much success. What happens is as follows:

• I create an enchantment (leaving everything on the default)
• The enchantment type is set to "BREAKABLE"
• I compile, launch the client, and put a vanilla tool in the enchantment table
• After a few enchantment cycles, a slot will appear in the enchantment table that will be empty (hovering over this slot will not show a tool tip and cannot be clicked on)
• The custom enchantment will not show up

This is extremely frustrating as I cannot move forward on working on the mod until this is resolved. Thank you.