This would be a question that most people could not answer unless they were involved in someway with a television show or series of shows that was cancelled before it was aired to the public. It does happen.
I can recall a long time back being invited to be part of a television audience where a series called, Brass Monkeys' was being recorded for television. The series was going to be a comedy based on a group of men stationed in an Antarctic base. I was invited as an expeditioner who had actually experienced this. I guess they were after my opinion.
Anyway, the show seemed fine to me. However, for some reason, probably financial, I expect, it never made it to the the television screen.