Hello,
I’m having a very strange problem. I currently have 5 ScreenGuis in StarterGui, but upon playing the game that reduces to 4, and it’s always the same 4.
StarterGui:
In-game (PlayerGui):
None of the scripts deletes any of the ScreenGuis. I’ve noticed that it’s always the same one getting deleted; the one called “ModeGui”. It doesn’t matter what I name it, only those 4 remain.
Any help is greatly appreciated. 
Have you checked the properties of the ScreenGui that disappears?
They are the exact same as all the other ones’ properties.
You give is too little info to help you as best as we can, but I’ll try:
You said the script inside ModeGui doesn’t delete it, but what if you disable all scripts inside of the ModeGui.
If the gui does appear, the problem is in one of the scripts. Otherwise there is something different, but please try this first!
Nevermind, I have fixed this myself; this certain behavior was occurring because of the game’s settings. (I forgot to make it abide by the game’s rules)
Could you expand on this, so if other users have this problem, we can know what’s happening?
Basically, in my game, when the player first joins, their character does not spawn which means they do not get the UI, meaning I have to manually give it to them using a script.