The desktop has a “refresh” button to sync mail with the server(s). There needs to be such a feature on the mobile version. I am trying out the Android mobile version and my inbox is out of sync with the desktop. I can’t say if it is just a syncing issue or if some emails are deleted/not deleted in the mobile version.
Learned from another post that swiping down on the list of emails will cause the refresh. Maybe a guide that links actions on the desktop to how to do same in the app would help.