I have a strange situation. 
We have a configurable product with 2 dropdown options. Colour and Size. 
After creating the product and saving it. we go to the associated products tab. 

When we add products via the Quick Add feature. We do get all the signs of a functioning system. Although the product seems to be added under the options, in the table beneath there is no action. after saving the product all is gone. The simple products are created perfectly. No errors in exception, system or apache logs.

I added a photo.

![Items not added.](https://i.stack.imgur.com/6V1O5.png)

EDIT
Good to mention. that the site is full of configurable products (shoes) those have just 1 configurable item (size) those work without any problems.