Since the past Thursday (Oct 15th) I have been seeing regular problems with 11.1 and 11.2. I first noticed the problem during Parks and Recreation sitcom, and has continued consistently every minute or so since then.
On both 11.1 and 11.2, there has been a regular and frequent brief video and/or audio glitches, similar to a poor reception issue but not identical.
This is not a reception issue -- my signal strength is incredibly strong (93 or higher consistently), and has been strong for the 1.5 years that I have gone OTA. I am using a very high rooftop antennas with clear line of sight (no trees or buildings anywhere near) -- separate antennas for UHF and VHF, neither amplified, Pico-Macom diplexer/combiner running into CAT6 wiring to a single CECB converter box. The setup has worked flawlessly and still does -- except for this nuisance WPXI issue that I started noticing on Thursday (although it may be started a day or two before, as I did not watch WPXI much those previous days).
I have troubleshooted this down to the point where I believe that it must be a WPXI issue, albeit possibly some obscure incompatibility with either of my 2 different converter boxes, a 1.5 year old TR40-CRA, and a brand-new 2nd generation DTVPAL PLUS (which, to my understanding, has a completely different tuner than the TR40CRA). In fact, the DTVPAL PLUS was still in the box and I just unpacked it today to troubleshoot this issue.
Thinking that maybe the signal was too strong, I also tried inserting a splitter into the line to drop the signal strength, which dropped it from the mid to high 90's down to the lower 80s, and the behavior was the same.
I also went to Radio Shack and bought a brand new diplexer/combiner, with identical results.
So, having eliminated every piece of equipment, tried attenuating the signal, and the fact that nothing had changed on my end and all other channels are receiving perfectly, it seems as though something must have changed at WPXI.