Bottom of Page 5 for spawning:
"... Then for each missing
supply objective, roll ..."
I'm assuming Missing means the objectives, you've already resolved?
Then it goes on:"for each die that cannot be rolled, increase the track by 1"
So the only reason in this case you wouldn't be able to roll a die is if you have too many that are already showing Darkness faces in the pool?
Note: Yes, I deleted the double "that that" in the quote