Language is missing in Product Display node that has been created directly from the "Add a product" form

When I create a new product the usual (Commerce core built-in) way, and reference it to a later manually created Product Display node, everything is fine: The node has its language set to "und". The attached screenshot shows such two nodes in the admin/commerce/products/display_manager table: the first (101) and last (104) item.

The other two nodes shown in that table (102 and 103) have nothing set as language. Those nodes have been automatically created on the "Add a product" form, by clicking "Add a reference to: New display node". These nodes are problematic. Their URL alias (automatically created by the Pathauto 7.x-1.2 module) cannot be changed!