Dynamic View

In Dynamic View, I set filters by column values and then restricted the view by that filter. However when I go back in, filter has a red explanation point and is unavailable. So the restrict by filter view greys out and now anyone with a Dynamic View sees everything on the master sheet. Why is this happening. It is happening on multiple Dynamic Views and is frustrating when the restrictions disappear. What dictates what columns can be filtered in Dynamic View? And why are certain filters becoming unavailable?