New OTA channels appear then disappear

OK, I may not have thought this through well or maybe this is normal but here goes. Last night I decided to do a channel scan on my Base Roamio that I use for OTA. The scan turned up 56 channels, 6 more than I had been getting. The new channels were all from one station, so six channels being broadcast by one station. I went into my channel list and check marked the new channels and then tuned into each of them. They were all up and working just fine, even started recording one channel. They showed up in the guide with the station info, but just showed "To be announced" in the program guide. A bit later I went in to see what the signal strength was for this new station. It was only 40%, so I was surprised I was receiving them with no pixelation. I went to tune one of the channels again about 10 minutes later and got the message "unable to tune" or whatever the message is when the channel signal isn't strong enough to lock. I wasn't surprised given the low meter reading I had seen. I then went back into my channel list and now the station/channels weren't even in the list to select or deselect. They just disappeared.

I just don't ever recall channels just disappearing from the channel list. Also why they came in perfectly for awhile and then just nothing over a period of less than an hour total. Seemed a little like a Twilight Zone moment to me. I had gone in and cancelled and erased the one channel I was recording. The only proof I have that I'm not hallucinating is that I took a picture of the channel scan showing finding 56 channels as I was pretty excited to pick up that many.

So is this normal?