Sometimes osage does it, sometimes not! My experience. Since I had it first time I do the heating of Osage from that time on only with dry heat. I rub it with with muscrat fat (any other animal fat will do) and then heat it with a heating pistol? (correct word?).
The fat helps to heat it slow and even and helps not to burn up the wood, although you have to be careful!
When its cold you can keep up work, otherwise with steam it takes up to 2 weeks of waiting.
You can put hideglue into the crack and then wrap it with animalsinew. This will, after it had dried, shrink and hold the wood together.