X1-A cable/dvr box experiencing ~2-3 second lip-sync issue on ONLY
2 companion channels 003 & 803 which are ABC (WSBTV) in Atlanta, GA.
All other channels have no lip-sync issues. Is this a known headend problem or X1-A box firmware problem?
If it's only those channels, then it's something upstream and not your box itself. Given all the compression/re-compression/channel packing going on, it doesn't take much for audio and video to get out of sync. If it's still doing it, and you know somebody with an antenna or non-Comcast service, you can see if they are also seeing the problem.
Once I changed the Audio setting on the X1-A box from "Stereo" to "Expert," the Lip-Sync issue was corrected for channel 003 and 803.