You can check your bank 's website. Your account may have messages, notifications, or alerts that needs your attention. Any sign-in issues in the bank's website for any announcements can block QuickBooks from downloading new transactions.
Besides, if you make changes on your bank's website, update your bank info in QuickBooks.
Let me show you how:
Select the blue tile bank account.
Click the Pencil icon.
Select Edit Sign-in info.
Update your info.
Then click Update on the Banking section to ensure the bank downloads the latest transactions.