I don't believe that you have configured your Option Names and Option Values correctly so your Attributes are now wrong ...
You need 1 Option Name: Size
Set as an Option Type: Radio Button
Now make your sizes as Option Values where you select the Option Name: Size and then make your Option Values and add your default Sort Order
Now go to your Product and add the Option Name and each Option Value separately ...
This will give you the selectable Radio Buttons ...
NOTE: be sure to set a default



