I have an Outlook.com email address and am using Office 365
I have two devices. A laptop and a Surface tablet. Both running Windows 10.
I have set Outlook on both of them to use Imap (Exchange)

Suddenly no new emails are being displayed on my Surface tablet. At the bottom of the screen is the message "This folder was last updated at [time]
But the last emails displayed are dated Saturday!

What could cause this?
How do I correct it?

Thanks in advance