Although I believe there is a different way to do this that will work correctly like Achileon mentioned below, we prefer that the editor handle something like this a bit more gracefully and not just crash.
Where are you moving the static mesh into the the box? In the blueprint viewport or are you placing it in the level? Neither reproduce a crash for me. Would you be willing to create a small test project?
Open the blueprint class BP2, then in the blueprint Viewport move the static mesh slowly toward the collision box, it should crash the editor when the static mesh hit the collision box.