If you're having trouble splitting large PST files or need to split them, I recommend using Advik PST Merge Tool instead of the manual method. The manual method has many restrictions and limitations. This application allows you to easily split any size of PST file into smaller parts. It's compatible with all versions of MS Windows. To learn more, download the free demo version of the program.
Learn More: https://www.adviksoft.com/pst/merge.html