September
Long story short, i have a Hisense Roku tv I noticed tonight after watching tv the channel froze up and pixelated. After going through a number of resets on both the modem and the tv box the cable box will work fine for less than 5 minutes then when I go to change the channel it the picture freezes again. I should mention we have a total of 4 optik boxes in the house and this is the only one we have problems with.
September
See if you can reset the TV.
A friend of mine had similar issues with a TCL Roku TV and had to do that to get it working properly again.