Windows 10 - System Tray Icons Won't Hide

I discovered the solution by trial and error / accident.

Google-fu suggested that this registry key:


was related to numerous Tray related problems so I looked there and found a REG_DWORD entry labelled:


which was set to 1. I changed it to 0 and restarted Explorer et voila my system tray starts working again. I've no idea how this got set in the first place, but I'm happy now anyway.

This link tells us "This setting determines whether the items are always expanded or always collapsed." which sort of suggests it should be controlled by the Win10 option "Always show all icons in the notification area", but toggling that option had no effect for me - even with Explorer restarts.