Good to know. Have the same problem on my butternut vines.Check near the base and see how the main stem looks - you might have a borer or split vine. If thats the case, I've had some luck mounding dirt over the vine until the next leaf union.
How to Repair Broken Squash Stems. As you survey your garden, you may realize that some of the rapidly growing stems, or vines, of your squash plants (Cucurbita spp.) have split or broken. Squash vines are hollow and easily damaged when they are moved and when cultivation takes places near them...homeguides.sfgate.com