At Outlaw's suggestion I'm going to do a full system reset in hopes that will resolve the problem but if not they've asked that I send it to them to check it out.
Until I do that I have been prepping to replace the HDMI cables with fiber optic versions from my gear to display. The previous cables were were spec'd for 1080p and in the wall. The opportunity to replace cables occurred because I had a plumping leak in the same wall as my cable runs and I had to remove drywall to get to the leak. I'm determined to get something good from having to open up the wall! FYI the fiber optic HMDI cables work well without any handshake issues.
Outlaw 976 | ATI 2005 | M&K 850s Left, Center & Right, Surround-55s, MX-70B Sub | Harmony 950 remote | Panamax 5100 | OPPO UDP-203 | LG OLED55B7