Hi,
After sleeping on the issue I found that I'd ticked "Featured product" - so of course the filters didn't show! After unchecking everything are as desired :-)
I added a bunch of products with specification attributes for testing - the filters displayed nicely on the catalog page.
Then I deleted the test products and added the correct one (with new specification attributes) - but now the filters are not displaying. I can't find what I have missed....please assist me.