This is a recent problem so I think it got pushed with an update.
I have a USB audio for my headphones and the onboard audio for my speakers. I usually sit on my speakers and I put my headphones on when I get a call. Default device is speakers and default communication device is the USB headphones.
Right now the ringing when receiving a call is sent to my headset (which is on the table) but the ding that notifies me that I missed a call is sent to my speakers. This is why I am assuming it's a bug.
I thought about setting the secondary ringer but that only allows the headphones to be set which are already my primary speakers so that option seems pointless.
Cycling through or disabling/enabling audio devices doesn't seem to fix it, once I return to the old configuration I'm back to my old situation. The only thing allowing me to receive calls is the phone on the desk ringing letting me know that I should answer on my desktop.