We have an article that you can follow especially mapping the columns and the required fields. Please check this out: Import your bills in QuickBooks Online. If you currently following this, please contact our Support team. That way, they can do a screen-sharing session to see your setup.
Click on Help and type something like importing bills.
When you get search results, type in I still need a human.
Select from any of the results again, and click I still need a human.
Click Contact Support team and choose Chat.
You can always go back to this thread if you have other concerns.