@Jackill, from your conclusive experiment it seems that something goes wrong on inactivity. Thus it might be interesting to test:                         System Preferences > Energy Saver > Power Adapter                                 and as a bug hunting method, try the different settings which might block any thing which is fired upon inactivity.

@JacksonSox this is a developers only web server. Some of them are working at Apple, but this is not an official Apple professionnal grade support web server .                                                                                                                         If you want to report a bug, I suggest you to go the official Apple professionnal grade feedback web server:     https://feedbackassistant.apple.com/