I know it's been a long time, but I want to post a solution here for people in the future.


Instead of the `important` label, you should use `^iim`. https://mail.google.com/mail/feed/atom/^iim

You can find a list of special gmail labels like this [here](https://developers.google.com/gmail/android/com/google/android/gm/contentprovider/GmailContract.Labels.LabelCanonicalNames).