Today is the 3rd time I've had this issue where I change channel and in doing so lose all channels.
I unplugged the TV earlier and the channels returned (after scanning) but they have twice since gone again including right now.
My experience of Samsung phones led me to choose a Samsung TV but I am now starting to regret this choice. I've previously posted regarding intermittent recording to the attached external USB hard disk drive when on standby. I feel the Samsung TV is not a good purchase.
I have a similar problem. Every now and then I lose channels. I retune. Check software update. All OK. Then a few days later I lose channels again, not always the same channels. It appears that I am not alone.