Hi Andrew,
It is the cold. The two specific, recent nights cold is knocking them down.
The in-ground plant's leaves are hanging like basil and most garden plants after a near frost.
It is supposed to go back into the mid 60's next week
First they curled, then start to hang after the last two days. Before that several were trying to hang on.
Did you ever find the critter in your garden? My corn got wiped out like yours, as soon as they were ready.
Turned out to be rats/swamp rats. two days wiped out a 8' square section. The plot looked like the picture you posted. No foot prints, and I am pretty sure the suckers burrow also.
Used poison blocks, Tom Cat, huge suckers, they even stored hot peppers in my shed.
Good Luck, Mike