To resolve these synchronization issues, I would like to refer an inbuilt tool "OST Integrity Check". Before using this, please exit from MS Outlook and start OST integrity check tool. It is an excellent tool, but takes a lot of time.
So to save your prestigious time, I would like to refer an excellent third party solution, Convert OST to PST. It is a quick and effective solution to easily resolve all kinds of issues related to OST files. For more information about the software, visit- https://www.nucleustechnologies.com/datarecoveryblog/deal-with-synchronization-issues-between-ost-and-exchange-server