Reports: Products Purchased resets when product quantity is updated

[dhbearguy]

Version 1.5.1
NO Upgrade
Super Orders Plug in added
One Click (DreamHost)
PHP Version: 5.3.13 (Zend: 2.3.0)
Noticed right away
Tested before live.
https://store.sfmoviebears.com
Searched FAQ
Searched Forums.

When I update the quantity of products in my store, the Products purchsed report resets to 0.
The Products Low report shows correct based on sales.

Please advise.

[DrByte]

I just did a fresh install of v1.5.1, including demo products.
I logged into the Admin and looked at the "Products Purchased" report.
The first item there is #46, "Mixed Products ON with attributes", showing 18 sales.
I then went to that product in the Admin (actually, clicked on the product name in the report so I could jump directly to that product) and changed its quantity from 981 to 2222 and clicked Update, and then Save.
Then went back to the report, and the report still shows 18 sales, and all the other products in that report are showing the same as before doing the update.

So, it makes me wonder: What's different from my brand new fresh clean install of 1.5.1 which has no problem, and yours which does?