I'm still not sure this is a Dominos issue, I'm trying to pinpoint it, hence why I'm writing this.

Because Dominos is still having some issues for me, like the spells with dropdown (Summoning pets on warlock for example) not working, and those new types of spells on the new race that have multiple levels not showing the levels yet, I've disabled Dominos for now, and the first thing I notices is, where the hell is my cast bar?

When the prepatch first came, since Dominos was going to be dropped I tried the new standard UI, and the cast bar was there. Now I was using Dominos again and when I disabled it, no cast bar.
I go into edit mode, cast bar is enabled, I disable and enable again, no cast bar, I move every other UI element in case it was somehow hiding underneath one of them, nothing.

Is it even possible that it got disabled permanently?
I've made some addons so I'm not completely ignorant to how this works, so my immediate response to that was, no way.
When the UI loads, the game runs all the code, and if the addon is disabled, whatever it is doing to hide the default UI isn't run... unless it's being saved in some config.wtf or config-cache.wtf or any other CVar file, but I can't find anything on any of them.
The only frame I'm missing is the cast bar, nothing else is missing.

So, if someone can give this a test (disable Dominos on a char you were using it on to see if it's also gone for you) or give me ideas to what it could be or how to get the cast bar back and fully functioning, I would be very appreciative.

I have confirmed that it is NOT Dominos causing this... It was Plater.
There is a Hide Blizzard Player Cast Bar in there and for some reason it was enabled. Why a nameplate addon has that I don't know but whatever, this was the problem.
Just in case someone else uses that and had a similar problem.