So I use many mods that add many enchantments. What I've noticed is that anytime an enchantable item is in the advanced enchanting table, the list only shows 18 enchantments. I've tried it with a bow, an axe, and a sword (all of which have more enchantments possible than the ones listed). Not sure if this is intentional, but it makes it impossible to obtain many enchantments through the use of the advanced enchanting table.

I've noticed this as well. I was trying to add this to RLCraft which uses Rin's So Many Enchantments and the list is extremely limiting for things like swords. I couldn't figure out what was wrong until I saw this comment.

I Encountered the same thing, and I found that you can bypass the 18 enchantment list by using mouse scroll wheel. hope this helps anyone with the same issue.