I’ve found that this is related to changing the map size. For me, generating the small (3 player) maps does not crash the editor, but any other size will. Like mentioned, it generates the first time but then crashes on the second. I’ve noticed my game has also become very slow since the crashes.
I am having this issue as well, which lead me to this bug report. I played with it a bit and stumbled onto a potential workaround. Not sure if it will work for anyone else. Some steps might not be required, but this is what I did the time it worked for me. After doing this, I was able to generate many random maps in a row without the game crashing.
Start game, open up editor
Generate a random map using the default size (small I believe)
Check the box next to “Extend Map”
Under “New Map Size” choose the size you want your random map to be
Hit the button “Generate Extended Map”
Select the random “Map Size” and “Random Map Location” you really want (back over on the left side, not in the Extend Map area)
Hit “Generate Map”
Go to #7 until happy with what is generated (or the game crashes )