Alright, thanks!
I am, and it's highly unusual for my computer to have issues like this. Pre-18w19b worlds load just fine though.
Say, are you having issues with creating worlds in 18w19b?
More than just 18w19b, this goes back a few versions.
This is very unusual on my computer, which is why I classify this as some kind of bug.
*Updated to fix grammatical error