I agree about the vine borer. I planted my garden at the end of may and all I heard was that everyone has too may squash si I only planted two squash and two zucks.
Then all of a sudden they started to yellow and die and I didn't know why. They died down to the stem and miraculously came back.
I now know it was the borer because they came back
when I noticed that some of my leaves begin to yellow I looked for the tell tell sign( yellow sawdust like stuff) on the stem of the plants.
My husband opened the plants and pulled four out of different places on different plants. One of my zucks died completely and I pulled it out.
At the moment my plants are big but wthout flowers. Hopefully they will recover. I hope you find your problem.