VarAC has been working flawlessly for me since last December, UNTIL a couple of days ago. To my knowledge, there have been no Windows 10 updates recently.
Before I fully understood what was going on, I changed every setting I could think of that would cause audio to go out to the sound card on the radio, as opposed to the PC built-in sound system.
I set Windows to "mute all sounds" when communications were detected. I set System Sounds to "0", and also changed several other parameters I can't remember right now.
It FINALLY dawned on me today, that what is happening is that VarAC is sending it's sounds ("doorbell", etc) out the USB connection to the 7300.
I am running the latest version of VarAC and VARA-HF.
Has anyone else run into this, and if so, can you hopefully suggest a fix?