Why do the movies I have marked as having been "Watched" become unmarked repeatedly?

It's random. It applies to ALL the movies I have watched over the years. As an "Official Xfinity Employee" you must know that X1 automatically marks movies/TV show episodes as having been watched as you watch them and it also gives you the option of marking movies/shows as having been watched manually. It is extremely useful as it is impossible to remember everything I have watched over the decades I have been a Comcast cable customer. But not all the movies/shows I have marked as having been watched do not remain marked permanently. I can't count how many times I have remarked a movie or show only to have it randomly become unmarked again and again and again. Give it a try yourself. Get out your Xfinity remote, open the onscreen guide and start marking all the movies you have watched as having been watched and give it some time - they will randomly become unmarked over time. Guaranteed.

Why does the X1 system give us the ability to mark moves/shows if that designation will ultimately be removed?

@L1ngus, Thank you for that update, I appreciate it! We are aware of the functions of our equipment but we have to find out more information as not everyone is having the same problem. If this is happening to just you, we have to find out if it's an equipment issue or backend concern. If you could send our team a direct message with your full name, the name listed on the account (if different), and the service address associated with your account, I'd be more than happy to look into this for you. To send a Direct Message, please click on the chat icon in the top-right corner of the screen, next to the bell icon, and then type or select "Xfinity Support" to initiate a direct message.