Thanks for getting back to us, @12345CP. 

Let me join this conversation and route you to our Support Team to help fix entering SKU to select a product within an invoice in QuickBooks Online (QBO). 

Since you're still experiencing issues with entering products using SKU, I suggest reaching out to our Support Team. They can access your account in real time and use specialized tools to investigate the root cause of the problem. Here's how to contact them:

1. In your QBO account, then go to Help (?).

2. Select either of these tabs:

• Assistant tab and type Talk to a human.
• Search tab and click on Contact us to connect with a support expert.

3. Choose how you want to reach us (phone or chat).

For Plus, Essentials, or Simple Start, support is available Monday to Friday from 6 AM to 6 PM PT and Saturday from 6 AM to 3 PM PT. For Advanced, support is available any time and any day.

As a future guide, let me add this article to get helpful insights into your inventory data: Use reports to see your sales and inventory status.

You're always welcome to reply to this thread should you have further updates about entering SKU in selecting products in QBO's invoice window. We'll do our best to assist.