So if you disable your style everything works fine right?
Only thing I noticed is that you store reference to your button/text styles in a weird way.
&YagMainMenuWidget->YagGlobalStyle->YagButtonStyle)
Dont you have singleton instance of your “MainStyle” so you can access it anywhere in the same way without any other widgets references?
Take a look at shooter game Styles setup and try to reproduce it in your code (shouldnt be much work). Not sure if that will help but it’s the only thing I can think of.