Hi there, useromar.
Yes, you can filter the transaction without attachment. To do this, I'd suggest going to the Sales and Expenses page and filter the section to show the Attachment column. With this, the entries that doens'nt have the number in the Attachment column are the transactions without attachment. Also, you'll need to make sure that the attachment drop-down arrow is down.
From the Sales page, here's how:
You can click this article to see steps on how you can view all uploaded attachments: Attachments in QuickBooks Online.
Please refer to the articles below to see information on how the Sales page gives you a great at-a-glance view of the status of sales transactions, open invoices, and paid invoices. Then, how the Expenses page view and work with your company's money-out transactions.
Please remember I'm here anytime you have additional questions or concerns with QuickBooks Online. You can reach out by posting a response below. Wishing you all the best!