Hi .Wiech,
The reason I asked is because I can reproduce this in your map, however I haven’t been able to reproduce it in a situation without blutilities involved. If you have the MIDs set on event begin play in a new map without using blutilities, the delete/undo does not crash the editor. Blutilities are still considered highly experimental and unstable/untested. Try calling the MID switch from the construction script or event begin play without the blutility, do you see the crash occur?