Hello - Although I have not completely understand the problem statement, but I think grouping dimension and then exposing that as filter will work for you. Even if you have some older value in the dimension, but once grouped then you won't loose any data. Please provide any sample excel or work book to help me to further deep dive.
Any known issue with grouping from a calculated field? I have a calculated field which determines a persons statue either on board or off. When I go to group by true the option isn't available to me.