The blue button is a Pop up button that should trigger when you click the BUILD button, ths works fine, the button works, but when from this view i try to get toggle the Building menu and get back in game the BUILD button doesn’t work anymore, it doesn’t seem even to be to be affected by the mouse. I know that my blueprint is a bit messy, but I hope is still comprehensible.
After create widget node add some local variables like this:
Use this variable later in your code, so you make sure you are calling same widget you created earlier.
After doing this (and still not working), post how it looks like 
To make it more clear. Using this workflow you could take validated get and make sure your objects are not none like here after your first branch:
If control GUI is true, you dont have widget, but later you are trying to get IsVisible, and set Visibility on it. This is how you could use validated get and prevent this (or even log error on screen)
