I assuming you are talking about Season 10 Episode 14 on Catch up and no other previous season ?
S10 Episode 14 is showing available to watch on all my devices in the UK.
Where Season 10 Episode 15 is not scheduled to be added until next Monday the 6th of April after 10pm.
If you are talking about Episode 14 on Season 10 what playback devices are you using and are you based in the UK or are you a Republic of Ireland customer ?
Edit - Ignore the above i just realised that you are talking about all the previous Seasons of TWD on boxsets.
The Walking Dead: The Journey Conti
In anticipation of The Walking Dead's return tomorrow, join us for a retrospective of Seasons 7. Relive all the key moments in the show's history, with exclusive behind-the-scenes access.
Sounds like a glitch to me on your Watchlist where my understanding TWD Box sets left early part of March 2020.
Perhaps @Jason-C of the NowTV Team can confirm if there is a return date planned on his spreadsheet for TWD ?
If you have Amazon Prime Video account the last time i checked TWD Seasons 1 to either Season 8 or S9 was free to Prime members.
Thanks for getting in touch.
Sounds like a strange bug in My TV. Unfortunately, we have no date yet on when The Walking Dead will return. Sorry for any confusion.
The Walking Dead: The Journey Continues was a special which aired a few years back. It's possible the watchlist has gotten mixed up somewhere!
We'll pass this to the relevant team to investigate.