I have lots of flowers on my cucumber and squash plants. The foliage looks great but have only produced one yellow crookneck squash. I am using Miracle Gro all purpose fertilizer for vegetables, 24-8-16.
Growing Squash and Cucumber
Certified GKH Gardening Expert
Early on, squash plants will produce more male blossoms than female blossoms and, as male blossoms do not produce fruit, they often fall off. As the season progesses, you will get more female blossoms and more fruit. Here is an article with more information: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossoms-falling-off-vine.htm