[graviphoton]

It is what most of us intuitively expect from Play Next channel for series - list of episodes for started TV shows, one episode per show and exactly the next one after last watched episode of this show. Something like Continue Watching on Netflix (if I rememeber correctly as I tested Netflix only for limited time).

Well, what we expect and what we get are sometimes 2 different things. As we no longer have an Android maintainer, we are lucky that things work as they do and Koying added these features to Kodi before he left.    

I don't know how Android TV channel support is internally solved but it seems that mechanism only populate content of Kodi's playlists to the Android OS. If it is the case any improvement in smart playlist mechanism could be automatically used for channels. So there is a hope. :-)

Yesterday I jumped to Kodi 18 (latest nightie) I am eager to test and play with abilities of new version (my wife is not so happy I broke her rutine, interface is different and not all is working as it should).
I also noticed problem with season number. I can get list of last watched TV shows (easy). I can get list of last added episodes (easy) / movies in genre(s) (easy). But I did not find any obvious way how to limit episodes to one per TV show. (See images in Testing Kodi 18 alpha on Nvidia Shield Android TV.)
Maybe combining two smart playlists is the solution...

The UI (skin) should be mostly the same going from 17 to 18, there are a few changes in Estuary, but it should be mostly the same, unless you were using a different skin.    

Yes I have used my beloved Eminence 2.0 skin which is not yet supported in Kodi 18 and was automatically disabled after first run.

Exactly what isn't work right?

The biggest issue I have is generating false movies items with the same title when updating library. These entries start TV shows episodes which are not in movies folder/source (very strange). Cleaning library removes these bogus entries but after updating library they are back. I spent almost hour finding what is wrong but I didn't come to any conclusion yet. It needs further investigation.

Not sure what you wanted me to see in those images, especially since the first 2 are my screenshots (someone just modified the 1st for the 2nd).   As a matter of fact, all my Oreo screenshots.

It is only visual illustration for what I wrote.
Yes I used your screenshot for showing how much space could be gained (for my comment in SHIELD Preview Program forum). If it is not ok for you sorry I will replace it with my own.

You can't combine 2 playlists, not as a channel, and what you are looking to do probably can't be done, at least not the way you expect it to. Netflix for example does things differently, they show what's queued up. You can do that by adding a Episode type, and then using "In progress" as the rule. This will give you 1 episode per TV show, but the episode has be in progress. 

I think I will use last watched TV shows channel then (until better solution emerges). It jumps directly to series list which is significant improvement over old way.