shoot, sorry I missed this !!! now this is just the way I do it and there might be others with different ways..
so your humidity seems to be perfect.. I will start by saying, these snakes need a full year off after giving birth, that means you should only breed every 2 years.. that said
when you start the breeding season you can spray a little more often to stimulate a wet season and drop temps a little . I drop the temps a few months before by a couple degrees every week..
ok I was going to go with a full breeding procedure but you seem to have that part working
you should raise the temps at the hot spot once you know they are pregnant.. get a hot spot of 90 deg.. most females will stretch out their bodies under the heat source while keeping their heads lower in the cage..
by having a good gradient in the temps, they will know where to be.. I've noticed that my females would always stay on the hot side trying to get heat to have the babies develop ..
as I mentioned, others may have other explanations, but I think that keeping the 84 is too low, a gravid female need more heat to incubate her babies..
hope this makes sense !!
best of luck.. and if it works next time m let me know and I can give you pointers with the babies, they are some of the most complicated babies to care for..
Cheers
Steph