I just made a new list for a matrix items options, Small - Large shirt sizes. However, the list isn't appearing on the page of Custom Lists, nor as an option to chose from when trying to select it as the list for the matrix options.

Trying to create a new list says the name is already taken, so the list does exist. But if I made a mistake when crating it, I can't find my way back to being able to edit it, only the options inside of it.

This is what the custom list of matrix options looks like before saving it. I've made two, but neither show up anywhere they're expected to but are in the system somewhere.