Hello,
I am running Photo Mechanic Version 5.0, build 18359 (5034d39) and I run Mac OS X 10.12.4 (16E195) on my Intel-based Mac. My monitors never sleep when the app is running. It's the one app that shows up in Activity Monitor as "Preventing sleep". As soon as I kill it, my displays sleep again.
Is this a feature of Photo Mechanic? Are there plans to make this an option? Or any workaround?