Allow me to help point you in the right direction who can assist you with reviewing your CSV file.
Since you've downloaded the CSV file from Wells Fargo, I suggest getting in touch with your bank to have this investigated. QuickBooks depends on the information provided to us by the financial institution.
Also, I recommend reviewing your data first before importing them into the system to ensure there no missing and duplicate transactions. You can refer to this article for the detailed steps and instructions: Manually upload transactions into QuickBooks Online.
Once imported, I recommend editing, assigning, and categorizing your transactions. Also, you can match them to the existing entries in the software as well as a link to reconcile your account. Just go to the For Review tab from the Banking menu. Doing so will help you ensure the accuracy of your financial records.
Let me know how things go by leaving a reply below. I want to make sure your transactions are intact and able to import them successfully. I'm here anytime you need assistance. Have a great rest of your day!