Some transactions are missing from the bank transactions but are in the bank account activities/statements. what to do?

I appreciate you letting us know, Valerie. Allow me to provide necessary fixes when managing missing online bank transactions in your QuickBooks Online account.

Beforehand, may I know what specific banking institution is linked to your QBO account? Any additional information will get us closer to the resolution and check if there's an open investigation about your concern.

In QBO, the program is dependent on the entries downloaded from your banking account. Since updating your feeds doesn't work, I recommend checking out these areas on the Banking page:

• First, navigate to the For Review tab in QuickBooks. This tab is where recently downloaded transactions are stored. If you locate the missing transaction, assign it to an appropriate account category. Keep in mind that transactions will not appear in your books until they have been categorized.
• Next, check the Categorized tab. This tells you what happens to transactions you already categorized. Specifically, review the Added or Matched column. This tells you which account you categorized the transaction into. If you find your missing transaction, but it's in the wrong account, follow these steps to unmatch and move it.
• Finally, check the Excluded tab. If you mark a transaction as personal or a duplicate, it goes here. QuickBooks won't add excluded transactions to your accounts. 

Additionally, you can follow Steps 3 & 4 outlined in this article for more detailed information: What to do if you can’t find downloaded transactions in QuickBooks Online.

For now, you can manually upload your bank transactions to your QBO account as a workaround. To do this, you'll have to download the transactions from your bank's website in a CSV file format. Then, import these transactions once ready.
 

Once everything comes in handy in the future, you can start categorizing and reconciling your accounts to make sure they always match your bank and credit card statements.

I'll always be around in this thread if there's anything else you need further assistance with when managing bank transactions in your account. Keep safe!