In dead city where Bourbon sometimes gets stuck when he says "just one more courtyard" but just keeps standing still i have found the only way to continue is by either: reloading from last checkpoint until he moves when he says the line. The way i fixed it is by throwing a molotov at his feet and then jumping into it myself, a monster should spawn in the courtyard, jumping over a fence
The level was bugged since leaving the store where there should be monsters outside the windows, they didnt spawn, and when i crossed the river one of the flying monsters was just sitting on the ground with his wings unfolded (still alive).
Thats the same monster you can see on the other side of the fence when bourbon gets stuck.