Sometimes when plants produce flowers but no fruit it can be a sign of a pollination problem and is fairly common with plants in the squash family: cucumbers, squashes, and melons. Since these plants produce separate male and female flowers, they require bees or other insects to transfer the sticky pollen from the male to the female flower. However, you indicated that the cucumber plants were producing, so it may not be a pollination problem. Radishes, lettuce and beets do not require pollination.

You also indicated that the tomatoes that were on the plant when planted did not ripen. No fruiting and fruits that don't ripen could be a sign of over-fertilizing. The nitrogen in most fertilizers promotes leaf growth, not fruit development. So over-fertilizing, especially with a high nitrogen fertilizer can prevent fruiting or retard ripening.

Unfavorable weather conditions like temperature extremes and dry soil conditions can cause flower drop before fertilization.

Following are a few links to Univ Extension sites with more info about why plants don't set fruit:

https://www.ksre.k-state.edu/news/stories/2021/07/horticulture-heat-stress-on-gardens.html

https://www.extension.iastate.edu/news/yard-and-garden-when-cucumbers-tomatoes-peppers-dont-set-fruit

https://blog-fruit-vegetable-ipm.extension.umn.edu/2021/07/vegetables-not-yielding-well-blame-heat.html