Thanks for following up with the Community, IMP4. I appreciate your detailed information.

Error 350 usually invoices an invoice, journal entry, and payment. It will display when transactions aren't linked properly.

If you've only troubleshot with the verify and rebuild utilities, I'd recommend trying to delete and re-create transactions next.

Here's how:
 

1. In your top menu bar, go to Edit, then Find.
2. Under the Simple tab, use your Transaction Type ▼ drop-down list and choose Invoice.
3. Enter the invoice number mentioned in your error message in the Invoice no. field and click Find, then pick your invoice from the results. If there's no invoice number mentioned in your error, you can use a general journal entry number, or receipt number. Repeat steps two to three and replace Invoice with Journal or Sales Receipt. Access the transaction history from your Edit menu and choose the transaction.
4. On your invoice, hit Create a Copy. Be sure to change the invoice date so it matches with your date on the original invoice. No other changes should be made.
5. Press Save & Close to return to your Customer Payment screen.
6. Go to Edit, click Transaction History, then pick the original invoice and hit Delete.
7. Return to Edit, press Transaction History, then choose your payment.
8. Put a checkmark on the transaction line where the new invoice is located and confirm all related transactions are linked. If you can't locate your invoice on the payment details, you may need to re-create your payment as well. Repeat steps four to seven and replace the invoice with a payment. This new customer payment will contain your invoice details. Put a checkmark on the invoice line to link it, then do the same for journal entries.
9. Verify and rebuild your data again.

In the event you continue encountering error 350 after performing these steps, you'll want to try troubleshooting with our QuickBooks Tool Hub next.

If you still can't solve it with your QuickBooks Tool Hub, you'll want to get in touch with our Customer Care team. They'll be able to pull up the account in a secure environment, conduct further research, and create an investigation ticket if necessary.

Please feel welcome to send a reply if there's any additional questions. Have an awesome Friday!