We've upgrading our store to 1.9 and found a problem with configurable products.
There is an attribute set: "items by color and size" which includes color and size attributes.
If a configurable product is created with only ONE attribute selected - the product IS not displayed on frontend (it was before upgrade). The only possible fix I found is to manually edit catalog_product_super_attribute table and include second "missing" attribute from the set for the product.
Manual editing of magento DB, of course, is a bad practise.
I also tried to change set of attributes with community/Flagbit_ChangeAttributeSet extension, but no luck. Set of attributes changed, but configurable product looses association with children - they can't be added.
So I'm looking for help from magento expert who can resolve this issue. It will probably take couple of hours to figure this out over teamviewer.
Willing to pay up to 75$/h for the time spent.