Thanks for reaching out to us. Allow me to assist you in reconnecting your bank accounts.
First, I'd like to know if you received an error when reconnecting your bank accounts. I can provide you with an accurate resolution if you encountered one.
Second, you'll want to make sure that your QuickBooks Online mobile app is updated. Go to the App Store or Play Store and update it from there. Once done, refresh the accounts again. Click the burger icon, select Transactions, then click the Refresh button.
You can also resync the app. This can fix any issue that can result in banking errors. From the Gear icon, click Refresh Data, then tap Yes.
If the same thing happens, you'll want to uninstall, then reinstall the QuickBooks Online mobile app. I also suggest using a supported browser and re-connect your bank accounts from there.
I added some articles to see the list of common banking errors and how to fix them: