Just had three new set-top boxes installed: a Fios TV One and 2 Fios TV One minis
HDR notification always appears when watching on the TV One minis.
The notification never appears when watching on the TV One, even when renting a 4K title on demand. Could this potentially have something to do with the HDMI cable? The HDMI cable that was provided was too short for my wall-mounted TCL 75R635, so I had my technician use a longer but older "High Speed HDMI cable" that I had.
For what it's worth, I always receive "HDR" or "Dolby Vision" notification when streaming Netflix, Amazon Prime, etc., on this TCL 75R635.