Output to console in xcode intermittently fails

I am having an intermittent problem with print() statements and other console output not showing in the xCode console window. I'm writing an app in Swift under xCode 7.3 (also had problem with xCode 7.2).

I'm been developing the app for about seven months and the first three or four months I had no problem with the console window showing my print() statements. However, now about 70% of the time when I debug running in the simulator I will get no Console output at all. If I stop and restart the app in the debugger several times eventually it will begin working. This is not due to me not knowing how to display the console window, there seems to be an intermittent bug.

Has anyone else seen this problem or know how to solve it?

I have wondered if it might have anything to do with some of the libraries I'm using. Here is a list of my Podfile.

pod 'Alamofire', '~> 3.0'
pod 'SwiftyJSON', '~> 2.3.0'
pod 'PINRemoteImage', '~> 1.2'
pod 'HockeySDK', '~> 3.8.5'
pod 'SwiftCop'
pod 'Braintree'
pod 'KeychainAccess'
pod 'TwilioSDK', '~>1.2.9'

Regards, Keith B