Kindly follow below steps and check if that able to resolve the IMAP account synchronization issues in Outlook:
1. Right click on the IMAP ‘Inbox’ folder present in the Outlook navigation pane.
2. Click on ‘IMAP Folders’.
3. Uncheck the option ‘When displaying hierarchy in Outlook, show only subscribed folders.’
4. Click on ‘OK’ and close the window.
5. Once done check if the emails are getting synchronized into Outlook.
6. When all the emails are received, you may re-check the option ‘When displaying hierarchy in Outlook, show only subscribed folders.’
In addition, also set the ‘Root folder’ path to ‘Inbox’.
To do so go to FILE - Account Settings - Account Settings - Email (tab) - Change - More Settings - Advanced (tab). Under ‘Folders - Root folder path:’ > Enter: Inbox.