Are you using any other mods (besides race mods)? Anything that makes changes to the interface could be causing the codex to malfunction, so mods like Extended GUI could cause trouble.

Well I am using the mod to expand some of the GUIs.
Also one that changes the inventory window.

In that case, the issue is likely caused by one of those mods conflicting with the codex changes made in Elithian Races. The mod that changes the inventory probably won't affect this, but the mod that expands GUI windows is likely overwriting the changes I made to the codex menu.

I've flushed out all the mods I was using before and redid a new list and now the codex is now working.
I think it could have been the expanded UI.
I'll re-add that mod to my list and make an edit update on this post if it messes with the codex.

-=EDIT=-
Ok I've found the issue with the Codex being broken.
It was due to the Extended GUI mod.
After I subbed/downloaded the mod for a while the Codex looked normal but then it cut off what this mod adds in, in terms of adding the races in.
But after I removed that from my Sub list it began to look normal again with this mod's added content.