A few days ago, my Roku/TCL TV received a forced update (that cannot be rolled back) to version 8.1, build 4139. Since then, after powering off the TV and turning back on later, the Bolt resolution is forced down to 480p rendering the menu text blocky and hard to read. I did change the HDMI cable, put the settings to Recommended or checked the 4K box, changed inputs, rebooted the Bolt, etc. No help. The ONLY "fix" is to do a system restart on the TV. Only takes about a minute. After that, 4K returns and all is good with no other adjustments from me. Changing the TV HDMI settings has no effect (1.4/2.0/Auto). I have a ticket in to TCL. Doesn't seem to affect the Xfinity feed to the TV - it retains its 1080p resolution. Seems specific to the Bolt. (I swapped Xfinity cables and inputs too - no difference.) Just wanted to share here in case anyone else is having an issue. HAS to be related to the 8.1 roll out. Compare pics below (before TV re-start and after).