Good thought Robin, I've read about the spontaneous shedding of an ovary as well. That sounds like a good possibility but I hope that's not the case since I seem to recall that most birds only have one ovary? Is that right?
Anyhow OP I hope you continue getting eggs from this girlie, at least enough to hatch out a good dozen chicks before she gives up on laying. I'm hoping she pulls thru for you nicely. I'm not sure if this would effect your ability to hatch her eggs in the past. I would be inclined to say this specifically wasn't the issue. If anything I'd think this would be related to her producing eggs that weren't complete and unable to be fertilized in the first place. Which hen was this? I'm glad your vet bill wasn't a killer, you're super lucky to have an affordable avian vet that also works weekends at your disposal!