I've been having the same problem with tomatoes, cukes and zukes. After extensive internet research (at least 15 minutes), I decided it was too much nitrogen. My husband used lots of chicken pellets in the soil, and we water from our tilapia tank--double doses of nitrogen.

This time, we left out the chicken pellets, and there are a few cucumbers forming.

follow up: we got choke cukes, but few zukes or tomatoes.

I have a couple chayotes almost ready to plant, hope they do well...

Since I put up my thread the Chayotes have produced. All summer I had luxuriant vines, lots of blooms, but no chayotes, then in the late fall I had more than I could eat!. So I guess you need patients. Don't expect them to produce right away!

I think that the fruit development of the Chayote, is dependent upon the ‘photoperiod’ (length of exposure to light) of the plant. Even though I had lots of pollinators present, the fruit did not begin to develop until mid-October (here in Honolulu, Hawai‘i). This indicates, that the decreasing available daylight hours, was a ‘trigger’, for the development of the fruit. This phenomenon would probably occur earlier in the higher latitudes, to allow for maturation of fruit, before being curtailed by the first killing frost.

This comment was attached to an old ‘thread’, but it is still germane, to the topic of concern.