New mail keeps disappearing and reappearing
Every time I get a new email, it appears but when I click on it, nothing loads and it then disappears from my inbox.
I then have to go on gmail app to load it and it eventually comes back to Mail.
Try removing your email account from Mail and re-entering with what option you used previous ( You did specify what device you are using) . If you are using Hotmail or Outlook use the Microsoft Exchange option.