configurable products attributes not showing in layered navigation

Question

From this page http://boxchilli.co/s2as/kiteboard/kitesurfing/harnesses.html you should be able to see under the Filter By There should be Size however this doesn't show from the configurable products on the page

There is a part on the website were this does work http://boxchilli.co/s2as/gopro.html you can see the configurable product and the correct filters.

Whole site has been reindexed, Categories have been set to Anchor.

Answer 1

The attribute has been set so that it's available in Layered Navigation, right? In Catalog -> Attributes -> Manage Attributes each attribute has a frontend properties section. I'd have put this as a comment, but I had a screenshot so thought it might be helpful;

Edit

There is a difference between the two and you can see it when you add both products to cart (ie a harness and a test product). With a harness the option is lower case, with the test product it is capitalised. So maybe the harnesses are simple products with custom options (which can't be filtered using layered navigation) and the test product is a configurable?

Answer

Answer from comments -> The two products had different attributes.