Hi Hayley, what a shame about the beads. I hope you don't mind if I offer a theory. Your beads are too beautiful to give up so soon.
When I first made beads with the Devardi, I also got fracture similar to your beads and one of them also broke parallel to the mandrel. Since they did not appear to be the spider web type of incompatibility, I decided that Devardi may be similar to Lauscha and needed higher annealing temperature and slower cool down. So far the beads I made after I reprogrammed my kiln are fine. These 3 have Devardi baby blue, baby green, CIM celadon, copper green, V streaky sappire, dichroic, and a few dots of DH pandora. I will report back if any of them self destroy.
I will continue to test because I like the colors.