We can check the Audit Log to verify if there's another user who removed those invoices and contacts. Please see the steps below:
Go to the Gear icon.
Select Audit Log.
Look for the transaction, if it was deleted or removed.
If it's verified that other users deleted the transactions, the transactions can’t be restored. However, you’ll have to recreate using the details in the Audit log.
If none, let’s access your QuickBooks account on a private browser. We need to check if the issue is caused by the data in your cache. Once your browsing data stores up, it can cause performance issues in the web pages.
Check out these keyboard shortcuts based on the browser you're using: