Hey Angie -
A Tableau process called the "Backgrounder" does this work under the covers for you, and if you only have one or two Backgrounders running, they might be busy doing other things (like refreshing an extract, for example). If that is the case, your request will just sit there, as you describe.
It's likely that your backgrounders are "yellow" (ie: doing work). If you're interested in WHAT work they're doing, run the "Background Tasks" report on the same page.
You can refer to the Administrator Guide to learn how to add an additional backgrounder or two (it's easy)...or, just wait till the current backgrounders are done doing what they need to do, then try again (even easier!).
Hope this helps!
Thanks - that was helpful. I had some zombie tasks running that I saw on the Maintenance page. After a reboot, the permissions worked properly.