Hi, the bug is known (level loading crashes when Widget bound to viewport), but the workaround to remove it only works partially:
I have 2 widgets. The first is removed during play, and the second (containing only 1 textblock) is removed when(before) the level loads. The game still crashes. If I remove the second completely, it works (with the first being removed during play). But removing the second doesn’t work, even if I put a 10 sec delay between removing and loading new level.