Which journey and date ? It might be too early or sometimes when the train splits in the middle of the night the app does weird things. Always possible to add the journey manually but there's no need to until closer to travel.

Hello, thanks for replying, the tix are on 22 Feb, and 28 Feb.  I’ve tried adding manually but I guess it’s asking me to book.  I’ve already booked, have paid for a sleeper, so how do I add that journey to my planner or is that not possible because the planner is only for booking?  

The app can't book anything. It just reminds you that a reservation is needed and can forward to some of the websites where you can book.

Please mention route and departure time of your night trains, so people can have a look.