Succession worked for me where I just added it to My TV Watchlist from this link below (assuming you are a UK customer currently located within the UK).
Once added to your Watchlist it should get ported across to the Watchlist grid row on all your playback devices.
What playback devices have you tried and is there any error message or code ?
Also I am assuming you have the NOW Entertainment Membership and it's showing on your online account and you have signed into your NOW App playback devices with the same login details.
Another thing you could try is if using a PC or Mac then try a different internet browser and if using a VPN disable it.
Also going into the Entertainment section of the NOW App under "View All Entertainment" then from the next screen page go to "Channels" then go to the Sky Atlantic tile box, then pick up the Succession TV show folder from there also works for me.