We're seeing this error pop up when the app is trying to retrieve files. We contacted Box and they looked up the ID's, and they tell us the file ID's we're trying to pull belong to another organization.
We do successfully pull one user's worth of folders, but that's all we get in search results when we try search for folders.
We do successfully pull a lot of events, but we're pretty confident that we have more than one folder that should be showing up.
Did you try whats suggested on this link:
http://docs.splunk.com/Documentation/AddOns/latest/Box/Troubleshooting
Per the above link, I would suggest to rerun he setup after clearing the cache and making sure the user has the right permission.
I did. Well, I re-added the app on the Box side and started over. But I think that troubleshooting step is if you're getting permission denied altogether, and not selectively, like I'm getting. Most event requests work, some file and folder request work, just not all.