I am using Tableau 8.3 and there seems to be a bug where "show fewer values" hides some filter options that are not Null returns. This happened for me when I was using a quick filter over multiple sheets on a dashboard where some sheets would have no matches for those particular filter values but other sheets did. Using "show fewer values" then stays incorrect even when switching to a situation where ALL sheets will return values with the specified filter options, which can no longer be selected. Is there a custom way to replicate the filter dynamically showing only available options but correctly?
I imagine you could manually remove nulls using a calculated fields. Have you confirmed the bug with Tableau support? (email@example.com) If you've found a workaround, we would love to hear it!