To answer my own question in case others run into this, I realized the issue. Apparently in Tableau 10 if the URL filter does not begin with https:// (or http://, doesn't need to be secure) then it goes to workbook URL + URL you specified in your filter. Of course I haven't seen any official documentation addressing this change, but in my extensive testing this seems to be true.
I believe I am having a similar issue. I have a workbook that was originally made in version 8 or 9 with a Dashboard action that populates a webpage under my viz. In version 10.1 the dashboard actions only work when I open the workbook in desktop but simply does not when published to server. There is no difference between http and https links. Is this a known issue with 10.1?
Any update on this Issue yet? Has this been reported to Tableau as I am facing exact issue.