Spliting PDF

Thank you for reaching out with your question, and sorry for the troubled experience. 

Could you provide more details about what application or Adobe services you are using? Is there an error? Would it be possible for you to share a file with us? Lastly, could you share more about your workflow of how you split the PDF? 

Ensure your copy of Acrobat is updated, to check for any pending updates, launch Acrobat > Help > Check For Updates.

~Tariq