Directed Storyline Bug - can’t move forward.

I’m working through the Directed version as I’ve not finished it yet (been most of the way) and I’m now at the diner and waiting for the cook so we can eventually open the freezer. Zero zombies are spawning and obviously the cook hasn’t turned up either. I’ve driven back to our previous location in case there is a crawler there but nothing. 30 mins later and we are zombieless. Any ideas or is it just restart?