This is the culprit on my system. I have an HDMI monitor that is seen as an audio device by Windows 10 20H2. Even though I went in to device manager and disabled the (audio) driver, when my monitor goes to "sleep" with Cakewalk open, I get the same warning after waking it up. Mildly annoying. If you find a way to kill it off, I would like to learn the secret. Windows used to insist on setting HDMI to primary audio device every update, but disabling the driver fixed that. IDK why Cakewalk still "misses" it.