It should not show FY 2018 if you've enable the "filter to latest date value when workbook is opened"
Few thing reset the filter and apply it again and check. Make sure you've set the default fiscal start month date properties on data source as well as date field.
Else share some sample packaged workbook.
Thanks Mahfooj ! This is working fine in 2018.1 version. But for some reason, this is not working as expected in 10.3.11 version.
As far as I remember this feature was introduced in v10.3. I had implemented the same last year in v10.3 and it worked. I'm wondering why its not working in your case. Upgrade the version or you may raise a ticket to support team. That's what I could suggest.