Yea, that's likely what happened. We record a lot of shows and often never get around to watching them. Especially when it's a game show like this. The wife requests to record it, and never watches it and then eventually I get approval to delete the unwatched ones when I'm freeing up space.
This is probably part of the reason "Up Next" doesn't work for our habits. I like the idea of a section that shows me the shows I've started and not finished since that happens quite a bit to me. I also like my suggestion to mark which shows I want included in Up Next.
For example, we've been working our way through all three seasons of Narcos over the last month and often it shows up in the "Up Next" section, but often it doesn't. Since that's our main show right now to get through and finish, I would tag that to always be in "Up Next" until we finish it and move onto the next series.