Problems filtering dates
 

I have a column with dates, starting with 05-04-2018 in B2 and ending with 06-05-218 in B34. When I try to use date filters, and only want to see dates from May, is displays those dates + the last date, that is June 5th. No matter how I try to apply a filter, I do not seem to be able to get rid of the last date.

If i delete some of the dates, so that only a single date in June is shown, it is still shown if I filter on May. Even if I try to apply a filter that shows only one date, say 05-22-2018, the last date in the column is shown as well.

Any ideas how to get by this?

Jan