@Anonymous I just tried that and it seemed to work... Yay! I'm so relieved. Thank you. I'll try with the other two accounts that are also missing some data, and hopefully, it will work just as well.

Thank you so much for sharing those steps.
@4Gal , thank you for advising me to download the Chase data using a QBO file (I was able to do it directly from Chase without using a converter, yay). This, combined with the info from @Anonymous , made it so that I could upload the missing data into my QBO account. Thank you for taking the time to answer my question.