It could be a directory issue then. Try making a new map in the same directory as your menu level(if that’s what you’re using) and see if you can make it work with that.
And again, the second that open level node gets executed, the main engine thread will lock while it loads the level, open the level when complete and your MainMenuWidget goes bye-bye because widgets are not persistent through level changes. If you wanted to get fancy, you’d: OnClicked==>Show load screen image==>OpenLevel.
That way you’d have something interesting to look at while the main thread is hitched with loading.