Sometimes Outlook shows an error or never finishes syncing your subscribed mail folders, leaving you waiting and frustrated. This article explains common causes like incorrect server settings, automatic sync issues, and corrupted mailbox files that can make Outlook behave this way. When you see Outlook Stuck on Synchronizing Subscribed Folders, it can be because the Outlook data file (PST) itself has become damaged or unreadable. In such cases, the MSOutlookHelp PST Repair Tool can help repair the corrupted PST so Outlook can read it again. It offers different recovery modes for lightly or heavily damaged files, and it preserves your original folder structure, keeping emails, contacts and other items organized.

For more: https://www.msoutlookhelp.com/blog/outlook-cannot-synchronize-subscribed-folders/