Why does my Red Kuri squach have few female slowers and those it does have don't bloom but fall off?

Question

I have 2 Red Kuri squash that have a lot of male blooms but very few female. Those females that are showing up don't bloom (so I can't pollinate) and ultimately fall off without developing. I am in zone 5. The plants look very healthy with no evidence of pests or disease. They are in the same raised bed as a transplanted zuchini squash which is also not showing female flowers.