This almost certainly will not satisfy the desire that motivated your question, but just for the sake of thoroughness, we might notice that the 2014 TV show Ascension is about 70 people who believe they are on an inter-generational space ship going to Alpha Centauri, but they are really on Earth. The writers are mainly interested in exploring class differences, 1960s American society and a murder, and there’s very little treatment of “conspiracists frantically trying to keep the deception running”.
This almost certainly will not satisfy the desire that motivated your question, but just for the sake of thoroughness, we might notice that the 2014 TV show Ascension is about 70 people who believe they are on an inter-generational space ship going to Alpha Centauri, but they are really on Earth. The writers are mainly interested in exploring class differences, 1960s American society and a murder, and there’s very little treatment of “conspiracists frantically trying to keep the deception running”.
https://en.wikipedia.org/wiki/Ascension_(miniseries)
I watched it, and cannot even recall the motivation for the deception.