Its petty strange that the date range filter set to filter MONTH WISE (mmmm yyyy) is working on tableau desktop, but when published to the tableau server its showing date range filter to day level (mm/dd/yyyy).
Have attached screenshots for both the desktop and published version of the same.
Kindly provide some resolutions to this.
What version of Tableau Server is being used? An issue similar to this was fixed in 7.0.4:
I would recommend upgrading to the most recent release if you are not already.