Why Some Data are not Recovered?

Microsoft has set a limit on the PST/OST file size. So, please check if the output PST file size is close to that limit. If yes, then there are two solutions:

  1. Split the output file into several smaller ones. This is the recommended method.
  2. Increase the size limit according to Microsoft document. However, there are some errors in the document and the operation may not always succeed.