Automatic Warranty Scan for HP Computers

Automatic Warranty Scan does not occur for my HP computers.

I have 844 HP computers.

All of these computers are correctly picking up the Service Tag during scans.

I have used the "Feed Custom Data for Computers" tool to perform a bulk update and added the Product Number for these computers.

At the bottom of the Bulk Update tool, it says the following;

"The manually updated Shipping Date and Expiry Date will disable the automatic warranty scan."

I have not updated any Shipping Date or Expiry Date manually.

The automatic warranty scan does not occur.

I am running the latest service pack and hotfix version of Desktop Central, all computers have the latest version client, and I currently only have one management server.

I have tried the following;

I have a daily Scheduled Inventory Scan occurring,
Under the Scan Systems section of the Inventory I have used the Scan All button,
If I open each computer one at a time I can click the Scan button and have the shipping and warranty dates populated from HP.

I can't see any other way of triggering an automatic warranty scan. Please tell me I don't have to manually press the scan button for all 844 computers??