hi sorry i dont even know myself when the big memory leak occur exactly, and today the leak appeared two times without the game instance blueprint opened, but i was woking on some widget blueprint (user interface)
it really look like random for this moment, because i can work with widget for hours, without problem, and then today i had 2 leak while working on widget only
when the editor run slowly i look at the memory used and it is often ~9 000 000k and it stop to 9 000 000k, and sometime it goes overs 11 000 000k
and my projects are basics 2d games, without big confusing material or big skeleton mesh, just simple texture and sprites and widget for user interface
at this time i may suspect widget blueprint doing those leak as i use them the most in my three project
sorry for this poor help :>