When Enchancement and Zenith are both installed, the game fails to load the world, booting the player out to the multiplayer screen (even if it is a singleplayer world).

What mod is this?

Oh nevermind, I thought that said enchantment, it says enchancement. That is expected, both mods modify the enchanting system extensively. Not an easy way to get them working together, sorry :(

Is it possible to use Zenith for only the Affixes? I disabled the Enchantment module and it still breaks. Although, I imagine the problem is you can't wait to read the config before deciding to use mixins, or some shenanigans like that, I don't know Minecraft coding.

Do you have the crash log for it? It might be fixable on my end

Here's a crash log