That is expected. The edit inventories feature was added in a much later version, IIRC 10.5 or something like that. 

@Quan

Thanks for the quick reply :)

Does this mean that there is no way to edit, or use physical inventories from Epi Commerce 7.12?

working on a solution that requires us to identify (and toggle) items that are considered out-of-stock.  Is there another way to go about this in Epi 7.12 if we cannot physically adjust the quantity?

Inventory is a metric that is stored and tracked in all versions of Commerce. 

Before 10.5 (if Quan remembers correctly!) it could be read and modied through the Commerce Manager. It still can.

The new (new-at-the-time) Commerce UI enabled the inventory to be read.

Post 10.5, the Commerce UI provided update too.

You should be able to use Commerce Manager to do this in Commerce 7.12. 

You can write logic and use the API to work with products that are considered out-of-stock.

In most commerce implementations though, inventory is updated through an integration to an ERP or similar system. I wouldn't normally expect customers to be updating inventory through the UI.

Marcus basically nailed it. You would have to use CM to update the inventory information. Upgrading to latest version is a recommended solution.