I believe my issue is resolved.... and the TV cable box is suspect. The receiver unit was actually switching to the TV input, however the signal from the cable box via HDMI for lack of a better term, may have "fallen asleep" and did not wake up when reconnected. To determine this, I cycled the power to the cable box and upon reboot, the audio and video came through. I've replaced the cable box and after multiple attempts to replicate the issue, it hasn't failed yet. Fingers crossed.