Sending, receiving, and organizing email in Outlook.com
Hi,
May I suggest these steps:
Open Outlook.
Right-click Inbox → select Properties.
In the General tab, click Clear Offline Items → hit OK to remove local data.
Click OK to close the dialog.
With your Inbox still selected, press Shift + F9 to force Outlook to re-sync that folder.
you can use this link for more info:
I hope this Helps!