That sounds like it's losing gases during the baking then. Shorten the rise time and get it in a hot oven to solidify that crust. I presume you're brushing the crust with milk?
No, olive oil . Other ones have turned out fine. I'm leaning towards the 2nd rise time. I really like the no knead recipe that sits 12-14 hours then cook. However having some fresh hero size loaves is preferred.