I have the same exact issue
I am experiencing the same issue. I have tried doing an inplace upgrade on windows 10, using different audio devices and ports, reinstalling as LFX/GFX or SFX/EFX, using different versions of apo, removing and reinstalling drivers or fixing registry permissions. The issue persists. When I enable eq apo on any audio device or output. It enables sound enhancements which then mutes everything on the system except for system sounds. When I disable sound enhancements, I can hear everything again but eqapo...