Screen goes to sleep while in perform mode?

I have been using MainStage 3 for over a year without issue.

However, recently, the screen has been going to sleep while in perform mode, which is a problem when performing live.

Does anyone know why this would be? Is there a setting in MainStage that controls this?

I did not knowingly change any settings, so I am puzzled as to why this would start happening.

Thanks,

Kurt