Hey Rudy, any updates on this?
I am using 4.7.5 and got the same behavior. Holding down one key (or several at once) will autorelease as soon as i click a UMG button.
I hold down TAB for my score board, click on the button of the scoreboard and the release event of the TAB key will get triggered. And this happens with ALL keys. “Is Input Key Down” will also be false after this. It just releases every key that was hold before. 