Hey -
Though I wasn’t able to track down the exact cause, the problem with the main menu seems to involve the LevelsItemMatrix. Trying to compile the level blueprint or play in editor will cause a crash immediately, however removing the matrix from the scene outliner allowed the compile to complete although there were errors. You may want to redo the LevelsItemMatrix and the logic behind it in the level blueprint.
As mentioned earlier, there are known issues with using event binding in 4.6 that are being addressed for the 4.7 release. Another solution you could use would be to use a custom event call in place of the event dispatcher. Then you can make a call to the custom event instead.
Cheers