I have actually noticed that a few TV shows disappeared from my list. I have a couple of suggestions. Firstly, maybe the list has limited number of movies and shows you can add. Secondly, I heard that Netflix differs from country to country. I think that they purchase rights to stream some movies for a certain country and for a limited time period. It may also explain why your queue changes - maybe they prolong those rights...I'm not sure about that but I am not quite fond of the fact that I cannot find some of my favorite shows on Netflix. Think of changing to Disney+