I recently ran into an issue where after a few hours of working on my projects, begin play and tick would stop working, along with a lot of other weird behavior including pawn’s not responding to input movement.
After a few hours of troubleshooting and some other UE4 posts, i realized it was because I had created a gamestate that was a child of the base game state that didn’t have some functionality built in. As soon as I changed the default gamestate to the base (parent) one, all the odd behavior instantly resolved itself.
I’m just posting this to save anyone from some real frustrating troubleshooting!