Please make sure that your date and time settings are correct; if the date/time on an Android device is set incorrectly, Gmail personalization does not work.
To ensure IMAP is enabled for Gmail follow the steps below:
- Go to your device Settings
- Tap 'Accounts'
- Look for the Gmail icon and select 'Personal (IMAP)'
- Enter your account details (email address and password)
That's it, you should be all set!