Here you can try another third party OST to PST recovery tool designed to swiftly convert OST files to Outlook PST file format. The tool also provides multiple option to save recovered OST file like. In addition to migration, the tool also provides an option to directly migrate OST files to cloud based platforms such as Office 365, email server and web-based email client. It has a splitting option to split large PST file up to 5GB for users convenience. It has a smart search option facility to find out any particular OST file from a drive quickly. You can try its evaluation version to know the exact working mechanism of the tool.
more info- how to convert OST to PST file