QuickBooks is a great place to keep your financial records for your business. I'll be happy to assist you with figuring out what happened to the journal entries.
The only way transactions can be lost in QB Online is if they're deleted. I understand that this may not be you that might have deleted the journal entries but there's a chance that another user did. The good thing is you can verify what happened to those entries using the Audit Log.
The quickest way to view any transactions you've processed in QuickBooks is using the Audit log. You can see the changes made to your books and who made them using the Audit Log. It also tracks user login/logout activity, changes to settings, customers, suppliers, and employees. Since you're looking for what happened with the transactions, review the following steps for further instructions.
Here are the steps on how to access the audit log:
Give this a try and if you need further assistance, I recommend contacting our support team using this link.