I am having a similar issue. When I open the options menu using the * key I only have three options. Closed captioning, volume mode and accessibility & language. No way to add to favorites.
@Froghos, you don't add a favorite while watching a video. You have to do it before you start watching.
I’ve had the same problem for the past few months. All Channels doesn’t show the local cable channels but only the streaming channels. Every time this happens (frequently) I have to rescan for cable channels, it discovers 78 channels, go to manage channels where they now appear, hide the ones I do t want and select the favorites, and I’m all good until next time. Some of the hidden/visible channels are correct and most of the favorites are correct but not all of them. There doesn’t seem to be a pattern for when the channels are lost again.
I've found that if I just wait a day or two the problem seems to correct itself, the guide returns to the way it was. It must have something to do with updates.
This started for me as a problem with favorites but maybe the root of my problem is that the local channels disappear, not just from favorites but from the guide altogether. The only way they come back is to do a channel scan.
The TV has some “recollection” of them because I hide a bunch of them and after a rescan, some of those channels are still hidden, but not all.