I completely understand the urgency here, Hannah. Seeing $300k in open invoices that you know are paid is more than just a discrepancy. Since your bookkeeper has already confirmed that there's no discrepancy in your accounts, this is likely a data indexing error or a syncing issue rather than a bookkeeping mistake.
Since you need a technical inquiry (ticket) rather than accounting advice, please follow the steps in this article to connect with our Live Support team: Get help with QuickBooks products and services.
However, before you hop on the phone, try this one quick fix to see if it refreshes the page: Open your QuickBooks in an Incognito/Private window. If the $300k disappears, this is likely a browser cache issue. Otherwise, this could be a server-side error that requires further investigation.
Feel free to reply to this post if you need further assistance.
