I’ve done that every few months and then try to manually put them in. This has been a years long thing and they call themselves PBS 9 so I assume that means they’re still on channel 9?
KCTS will always be channel 9, but which radio frequency "channel 9" corresponds to can change. In the analog days, you could reasonably surmise that channel 4 was a lower frequency than channel 9, but that's not necessarily the case with digital broadcasting. It's the metadata contained within the digital signal that determines what channel number you see on the TV, not the actual radio frequency.