You can try Atom TechSoft OST to PST Conversion Software The software also supports to fix OST errors and recover all stored Outlook mailbox items within few clicks.
There are multiple third-party tools available on the internet, you just need to find the right solution. I have used OST to PST Converter tool when I required the same issue and got the accurate result. The tool works on all Windows versions. A free demo version of this tool is also available few emails can easily be converted into each format.