I am not a Tableau Server specialist but I managed other server applications before so...
I wonder what happens if you restart the tableau server process and the respective web server? Also what happens if you clear the server cache?
At a last resource... is it possible to reboot the box and see if that remains the same?
These are very basic troubleshooting options. I hope they can help you.
May I know, since when you are facing this issue? What is the version of the Tableau server you are using?
Please try out all the steps suggested by Rodrigo.