Why aren't season premiere's showing up On Deck?

As the title says, I’m having an issue of season premiere’s not coming up On Deck when they are added to my library.
It happens when I finish watching a season before the next season is available, then when it is added to my library, all is well, but it’s just not added to my On Deck.
I’ve changed my On Deck time to 52 weeks (1 year) and even though say, a season premiere is released 8 months after I’ve watched the last episode, it still won’t show up. But then if i navigate to the episode and watch it, episode 2 and all subsequent episodes then shows up On Deck.
I’ve heard that marking the previous episode as watched can cause this issue, as it doesn’t add a timestamp, but even if I actually watch the episode, it still does it.
Any thought would be greatly appreciated!

Don’t remove the last episode of the previous season from the file folder and the new seasons premiere will work as expected(show in the on deck)

This advise^ means nothing if you do not delete watched items as I do after they have been viewed.

On deck time is how long a unwatched episode will remain on deck(without watching) before it gets removed.

I don’t delete watched episodes.

I moved ‘Stranger Things’ to my ‘TV Sci-Fi’ Library and was quite disappointed when the next show didn’t go to On Deck. It’s fine now, however. In a few days when I finish S01 I’m quite sure it’ll go right to S02, but those are already on board. We’ll have to wait for ‘The Expanse’ next year to see what happens when S03 arrives - S01 and S02 are on board and watched.

Not much help at this time I guess.