I've had this problem on our local PBS affiliate (WETA), but only via my kworld ATSC tuner stick. Usually changing to a different subchannel and back again clears that problem.
My 722 hasn't shown your problem. Probably WEAO has screwed up their PSIP data in some obscure way. We've had real "fun" around here (Washington DC area) over the last year as stations figure out how to broadcast digitally. We've seen new subchannels coming on and killing the main HD channel, channels with no sound, channels with no video, and we once saw a main HD channel offered with an illicit video resolution. (The PSIP data was correct, it just wasn't one of the 18 modes valid for ATSC tuners. That didn't bother my tuner stick, but every TV out there seemed to exhibit a different problem including half the screen being lime green.)
You might try complaining to WEAO, but if they're like WETA, your complaint will never make it to an engineer. The PR weenies will capture your missive and deny that it's their problem. If they answer you at all.