On the last main mission at the hotel, I couldn’t tell what wave I was on as it was stuck at 0/4. But after destroying quite a few hunters and runners, it suddenly crashed.
Now I did have my companion with me so I’m wondering it that had something to do with it. On retry, I took him out of the battle and back into inventory. While the waves were stuck at 0/4, I still was able to complete the waves and finish the story.
I tried to send a crash a report, but it may have failed.
Here is a screenshot of the error…
Here is an image of the details of my system…
I’m on PS4 and had the exact same problem. When I had the crashes I killed the machines long before they even got close to the hotel (all hail the Experimental KVM59!) and I also noticed that the wave count did not work.
I thought that maybe something needed to trigger the wave count, so I let the machines get to the point were they stopped (to start attacking the hotel) and then killed them. This got the wave count to work and I could finish the mission. So try some patience if you like me kill the machines at first sight. 
I’m on PC (App Xbox) and this has never happened to me.
Did you mess with the game settings?
I think they already have the possible explanation.
I think the Mission needs the starting trigger to work.
If the machines don’t even come as close to trigger the trigger, the mission scripts possibly run into something like a NullPointerException which causes the game to crash.
So the mission should be changed in some way that it’s not possible any more… Like a few additional runners or hunters that fall from the skies directly into the mission area and trigger the trigger.
Nope, no settings changed. But I’m thinking that maybe its about the distance of the machines before it starts the count? Not sure, but at least I was able to beat it on the second time. The counter never changed though for me.
I would say that there’s maybe something to that, but I let the machines get pretty close. They were shooting the hotel and I was just running around hiding around the barricades throughout. So If they’re close enough to attack and damage the health of the hotel, doesn’t that negate the distance being a potential? I’m wondering if having my companion at the start, caused it to count as part of the machines on the map and it got messed up, because I picked it up and it was no longer in the mission? Not saying that’s the cause, just giving a “maybe”. LOL!
But if the machines are getting close enough to shoot and damage the building and my job is to see to it that its not suppose to get destroyed, if they shoot, I should be able to shoot back right? To stress, they were damaging the building and not so focused on me. I didn’t wait for them to attack me, they attacked the building.
Anyway, just a thought. It did have the one crash, it did NOT happen again. The counter never worked for me, but I was still able to win it! So nothing horrible, just reporting in case it helps in the future! 
Ah, I read it that way, that the distance also was a matter in your case.
Well the companion caused many other issues, too.
Why not here? Sounds plausible as you described.
I just wonder if it gets that much attention.
@Zesiir What do you think?
Well don’t get me wrong, I love my lil buddy! Sir Silver Fang is awesome! I just wanted to pass that along just in case it could be a potential part of the issue. I don’t know for sure, but just thought it might help if it could lead to other problems.