The most common cause of course is a pest issue - either SVB or squash bugs. Have you checked the plant over thoroughly for those issues? How about stem injuries?

Then assuming it doesn't just need watering I have to say that is a very strange looking BB zuke plant. Is it crowded in with something else that would cause that nest-like look of all those very skinny stems and smallish leaves? Or is it more than one plant planted very close together? I can't tell from the photo. Is the yellowish cast to the leaves accurate or just the photo? Up close exam for mildew? I see some yellowing leaves in there. Are they part of this plant or something else?

Dave

The yellow leaves belong to this plant. The older leaves were larger. The strange growth pattern is a newer phenomenon, since the last two weeks or so.