I've updated to 2020.01.19.2104 - same result?
Stop Channels DVR within the NAS drive and restart Channels DVR.
Stopped and started Channels DVR, rebooted NAS, no change... 
You do have some channels marked as favorites, right? And have you recorded any programs? Those two things are what are used to generate those lists.
You're guide is showing programs.
It was working fine until about a couple of months ago... but I'm confused by your comment - are you saying that new shows / seasons are only shown for channels marked as favourites? I'd assumed that it listed any programmes with a 'series premiere' tag or similar.
Is it - where?
All suggestions on the web admin are based on favorited channels. If you don't have any, then it won't make any suggestions.
I believe the "On Later" tab may pull in from all channels. But, I also believe the sub-tabs on the "Search" tab will only show favorited channels.
I find that even for channels I may not watch frequently—but still air content that I may wish to record—it makes sense to mark those channels as favorites so they are included in Channels' algorithms for recommendations on the "On Later" tab.
OK, thanks. I definitely have new shows on favourite channels - here's an example of one tonight. I'd expected this to be shown under the seach for new shows / seasons? (BTW, recommendations appear - it's just the 'new shows' search that is blank all the time.)
Our search for new season/shows depends on the "Series Premiere" and "Season Premiere" tags from Gracenote. It appears these are not being sent for UK listings anymore.
I just did a test, and it appears that everything on the sub-tabs under "Search" had at least one airing that was on a favorite channel. So, my unofficial, unscientific test indicates that the "Search" tab may only pre-populate with entries from favorite channels.
However, when looking at the "Recommended Shows" section under the "On Later" tab, I did find several programs that had no airings on my favorite channels. I also recall seeing "New Shows" and "New Seasons" sections containing programs that did not air on a favorite channel in the past. (Presently the only programs listed in those sections are on favorite channels, as the winter mid-season has begun.)
Is there anything I can do to get Gracenote to add them again? Failing that, would it be possible for the search to pick up programmes marked as new and episode number set to 1?
This can be achieved by creating an Advanced Rule.
I assume that will record everything unless we specifically tell Channels to ignore it? Might not pass the wife acceptance test... 
After you create the rule, you can check its matches in its list of upcoming airings. Use that list to open the page for the series to create a pass for that particular series. You can immediately pause your rule, and it will still offer a menu option to "Find Airings" so you can periodically (every week or so) check for new matches.
How did you come up with that New Shows List?
That's the "On Later" tab of the web UI.
In the latest prerelease I've fixed this by adding the Premiere tags back manually when we ingest UK guide data.
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