Thanks for the question, I will try to help you get to the bottom of this.
Some follow-up questions to help better understand what may be going on here.
1. How large are the cucumber plants?
2. Are there any disease or insect issues with the plants you have noticed? Any spots or discoloration on the leaves?
3. Have you observed both male and female flowers, or are you only seeing male flowers? (Or, do you know how to tell the difference between male and female flowers?)
It is normal for some female flowers to not produce fruit. Plants usually produce many flowers, and then abort some in order to ensure that they have enough energy to produce fruit. If the plants are struggling due to a lack of moisture, disease, or other issues, the plants will abort more fruit.
Another possibility is that the plant is producing very few female flowers. This could be due to a soil fertility issue or environmental condition.
Let me know those additional details and we can hopefully figure this out.