Xcode doesn't write anything to output console

Question

I am working on an iPhone/iPad app. All of a sudden output console stopped displaying ANY messages AT ALL. I tried to open older project - works just fine. So I thought that

Answer 1

This question appears all over the place and is a valid one pointing to a random bug in most versions of xcode. Obviously the majority of people arriving at these answers are just unable to use xcode and therefore credit the 'show the console' type answers. I have worked on a single major project for 6 years now and this appears every month or so. I reboot devices, restart xcode, stand in the corner singing yankee doodle dandy. Nothing has occurred to me as an obvious and repeatable fix. Eventually I will start work one morning and it will be working again. Nothing I have done will be an obvious fix, no updates will have been installed. Just a heads up to those thinking they are going mad.