This does not work:In the Choose a vendor drop-down, select the desired vendor. If an item has a Preferred Vendor, this is automatically filled on the Purchase Order.

Thank you for visiting the QuickBooks Community, pra9ma. I appreciate you for performing some steps to fix your concern. Please know that the issue with the re-order inventory doesn't prefill the preferred vendor on purchase orders is currently identified as an ongoing problem. Let me point you to our support to assist you further.

I suggest contacting our QuickBooks Online Support Team so they can add you to our notification list. This will help our engineers determine the number of affected users. You'll also receive updates through email once the issue is resolved.

Here's how:

1. Open your QuickBooks Account.
2. At the top right, click the Help icon.
3. Choose the Assistant section.
4. Type your concern in the Type something field.
5. Click Talk to a human.

You may also choose the Search tab and click the Contact Us tab. You'll then be routed into the What can we help you with? page. Then, select how you want to contact them and fill in the information.

Lastly, refer to this article if you need steps in running a report in QuickBooks that'll help you see all the open purchase orders: Create and send purchase orders in QuickBooks Online.

Please don't hesitate to leave a comment below if you still have concerns related to QuickBooks. I'm always around to help, pra9ma. Have a great day!