Haven't checked soft- or hardware squirrel detection algorithm yet to solve the mystery of absence of squirrels. However, I thought it would be no harm to show that The Squirrel Cafe is open 24/7. Therefore I've attached a sign to show just this:
[Update 2016-07-31] I've checked hard- and software today. The algorithm works flawlessly, no errors detectable. I've manually opened the lid and a corresponding tweet has been sent out which I've deleted thereafter.