Select "A". There is one surname, "Armstrong-Jones", the number of individuals is "6", and the link near the top is showing "Include individuals with 'A...' as a married name".
Click "Include individuals with 'A...' as a married name". The page will reload and that link will change to "Exclude individuals..." Now the number shown is "7". This is all correct so far.
Click on the "A" again to re-select the same list. The include/exclude link continues to show "Exclude..." indicating that the list of names should be including married names (correctly - since that is what we had just selected), but the number of individuals has reverted to "6", indicating the list of names is actually (incorrectly) excluding married names.