I don't know if it will work here or not. Just gonna say that upfront....but when we have a pair of fish that won't spawn, we introduce water from a tank we had some spawning in. The hormone signature in the water, even if a different kind of fish usually does the trick when all else fails. It's kinda my secret weapon to make problematic ones take the plunge. I have roughly 85% success with just this method. In fish, temperature, age, condition of breeders, diet, etc all play major rolls in breeding/spawing.
I did keep the FL blue craws for a while, and I know I had to watch the softness of the water, and sometimes add iodine to help with molting. Not sure if that was just because of my water or what there. When you have extra, I would love to aquire some if you're willing.