Yup, there is a problem. My boxes are the Insignia brand (AKA Best Buy - Zenith).
I checked out my Sony TV, and this is what I noted. Virtual channels 27-1 and 27-2 are broadcast on channel 29. Virtual channel 27-3 is being broadcast on channel 27 (which is virtual channel 66).
Virtual channels 66-1, 66-2 and 66-3 are being broadcast on channel 27.
The Sony TV works fine.
The Insignia boxes do tune to channel 66-1, but there is only a picture and no sound. No signal on 66-2 and 66-3, and they do not tune in via the programming scan. For 27-3, it does not appear on the channel scan. If I use the remote to dial in 27-3, the Insignia box then shifts to channel 66-1.