Q.cucumbers
I grow cuccumbers from seeds. This year the plants are just as beautiful loaded with blooms and cucumbers starting about the size of my little finger. Then, the cucumbers stop growing. They eventually turn yellow and die. But they stay in this stage for a week or more. The plants continue to grow and produce more blooms and fruit but all have the same fate. What is happening?
It sounds like a pollination issue. You will need to hand pollinate. Cucumbers are identical to melons on how they pollinate, so this article will also apply to cucumbers:
https://www.gardeningknowhow.com/edible/vegetables/cucumber/hand-pollinating-melons.htm