What is the food situation in the hives? Are there dead bees? Are their little tongues sticking out? A situation for me, being in Western WA, is that even though there is nectar available, the weather here has been bad enough that the bees weren't flying. I almost lost a hive that had lots of pollen, but had consumed their nectar stores. This hive, too, had a huge drop in bees, within days. I got syrup back on right away and now they are back to business.
Anyway, just a consideration. Good luck!