I appreciate you letting me know about how it got marked as the solution. I know that it is an addon issue, just not which one. Was hoping that someone on the forums might have encountered the problem and knew which addon caused it.
I’ll have to figure out what I’m going to discover the issue.
Thanks again for your help.
You have BugGrabber and BugSack - have you tried looking to see what Lua error they catch as your UI disappears?
Also, it can be a misconfigured WeakAuras script. Do you have some of the same scripts on both your computers?
There aren’t any errors that were “caught” unfortunately.
Also, the only scripts from WeakAuras are the default ones, which would be on both computers, of course. Right now, I’m trying with just ElvUI to see if my UI disappears again. That will eliminate one of the larger addons, at least.
Omg, I have been having the same issue for weeks now. My UI would disappear randomly and the worst part is when it happens during combat. I tried disabling some addons and even removed Elvui to see if that fixes it but nope, the problem is still there. It is definitely an addon or weak aura though. Just need to find out which one is causing me this headache.
So from my list in the first post, I’ve disabled all the M thru R addons. I’ve been going for almost 3 hours now without any issues. Going to give it a bit more, then I’ll start re-enabling those. So if you have any of the same ones in that range, let me know, and that might help us get it figured out 
Damn, who are you? You got literally the same addons as me. I will also try disabling the M to R addons and see which one is the culprit.
I don’t know if it would isolate things at all. But maybe showing LUA errors would help. Though I guess it’s possible that you’d not see the error either if it truly is full-crashing the UI
/console scriptErrors 1
Turn them off with when you’re done.
/console scriptErrors 0
Mind you, you may see errors that are unrelated as well, but it may help give you some direction. Or might not.
To Addons! The cause of, and solution to, all of your UI problems!
Hey, I found out the UI-hiding addon. It’s Missing Flight Paths. That son of an addon is the one which caused me so many headaches over the past month.
I can’t rule that out. but I’ve been running with that one on for a few days now, and haven’t had the UI disappear. The ones I’ve disabled from the main post list are: Mapster, Masque, PetBattleMaster, PetTracker (with modules), Prat, and Rematch.
With those disabled, I haven’t had an issue in the last couple days. Will continue with it as is, and will update in a couple days.
EDIT:
After more testing, I believe that Dedrastine is correct. Missing Flight Paths is the culprit. Even on the addons curse page, the author says it could happen. They will be updating when they have time to do so.
Ive noticed that when this happens to me its always during AV , Wintergrasp, and select fights in ulduar. Aur , mim and sometimes freya. hope we can figure it out , making me want to stop playing the game all together.
Did you notice this post was from May 21? So the information in it may be somewhat out of date.
I recommend you post on the Technical Forum which is where these sorts of issues can get assistance.
Start by disabling Spellflash addon. Once I disabled it, it fixed the issue.