Please check below screenshot showing in admin for configurable products for specific skus.
After page view, the source is giving the following errors.
<b>Fatal error</b>: Call to a member function getSource() on a non-object in <b>/var/www/app/code/core/Mage/Adminhtml/Block/Catalog/Product/Edit/Tab/Super/Config/Grid.php</b> on line <b>245</b><br />
As I researched about your error, a product attribute might be cause of this error.
To find out that attribute you need to go to error file --
app\code\core\Mage\Adminhtml\Block\Catalog\Product\Edit\Tab\Super\Config\Grid.php
and dump the product attribute code like below before this line $productAttribute->getSource(); at line 245 --
var_dump($productAttribute->getAttributeCode()); die("stop");
once you find out that product attribute, disable that attribute and then check your product edit page.
I hope it would help you to find out the exact issue.
This issue was caused by following reasons.
1. Attribute assigned to simple/child products.
2. Attribute not assigned to configurable products.
Resolved by assigning missing attribute to configurable products in attribute sets.