I'm here to help you reconcile your account in QuickBooks Online.
The transactions may have been reconciled that's why they aren't showing on the reconciliation window. Let's make sure they don't have the R status in the bank register screen.
Here's how:
Go to the Accounting menu,
Select Chart of Accounts.
Locate the bank register, then click the View register link.
Find the transaction. If the transaction is reconciled, you’ll see an “R” in the checkmark ✔ column.
You can select the transaction to expand the view. Then hit the box with the "R" until it's blank. This removes it from reconciliation.
Once done, choose Save.
Repeat the same process for other transactions.
If it shows blank in the bank register, you can open your QuickBooks Online account using an incognito window to isolate this. You may experience some browser issues caused by too much cache stored on your browser. Here are the shortcut keys: