I connect my QC to my macbook and open Logic Pro. Routing the inputs and outputs works fine for a while, but when I change project the guitar input stops working and I have to reboot the QC to regain the sound.
Steps to reproduce your issue:
Open Logic Pro
Open a project
Engage the guitar input.
Close the project and open another one
If I put the QC in stan-by and then change the project the problem does not seem to occur anymore. However, I also experienced that the guitar input drops randomly during the interaction with the Logic Pro Console.
I’m experiencing the same and found the reboot as the only method of restoring the audio. If you scroll through presets when the signal first dies and play, a momentary note can be heard before the signal disappears.