I had just opened up the beta of the 4.0 client, which then updated itself with a direct download package, which then told me that its trial period had expired. I then went to the Google Play store and downloaded the latest version, which is giving me this error after entering my master password, which it asks for when I go to synchronize with Dropbox.
There was an error browsing Dropbox (ERROR:DropboxUnlinkedException (null) (INTERNAL) [com.dropbox.client2.DropboxAPI.assertAuthenticated((DropboxAPI.java:2344), com.dropbox.client2.DropboxAPI.metadata((DropboxAPI.java:1626), com.agilebits.onepassword.sync.FileBrowserTask.doInBackground((FileBrowserTask.java:59), com.agilebits.onepassword.sync.FileBrowserTask.doInBackground((FileBrowserTask.java:1)]). Please try again.
Just in case, I also tried revoking the permissions for the two old apps from dropbox.com, but that didn't seem to have any effect.