Marking multiple movies as watched

The upgrade of my Windows HTPC from 14.2 to 17.1 went really well. But then I performed a clean library after which a bunch of films I had marked as watched were now unwatched. My unwatched count increased by almost two hundred. So I view my collection by unwatched to find the titles that shouldn’t be there, find one and mark it as watched. Then it jumps back to the beginning of the list. So I have to scroll all the way through my library to the place I left off to mark the next one. And do it all over again. Two hundred times.

I believe the last time I had to mark movies as watched it just jumped to the next unwatched movie (you know, in case I wanted to mark that one as watched also) Am I doing something wrong? Is there a better way to mark multiple movies as watched?

Thanks