TV Pixelation

Has a solution been found for the pixelation issue?  I am in SE Denver and have had the problem subsequent to recent network enhancements.  It occurs on HD live programs, but not on streaming apps.  A new modem was installed in December.  On March 4, I set up a new X1 TV box, including a new HDMI cable, and spent 45 minutes on the phone with an Xfinity tech.  All cable connections were checked for tightness, and she did a system refresh.  I just performed a system refresh today and the problem persists.  Thank you for your assistance.