Updated from 17.5.2302 to 17.7.2314 within the GUI.
Everything is fine expect that game mode settings are being reset on system restart.
I usually have only No Avast! Interruptions and Automatic Game Adding enabled (because I think its a bit ridiculous having an AV program mess with Process Priorities, Windows Update scheduling, Notifications) and everything is enabled once I restart the system.
Tried doing a repair from Programs and Features - Avast - Change - Repair but did not making a difference. Removed the component from Avast! for the meantime till this issue is resolved.