No replies to this? Wierd, it comes up in google search as well.

So the fix for most keys not behaving is to remove and clean the contacts 9/10. If older or having suffered some trauma such as being dropped or having things dropped on it, you might have hardware damage. The other uncommon cause of hardware damage is if something is fried inside.

Always take pictures after each step when deconstructing items for self repair, just in case. And lay out items in order from far right to close to your left.

• So the first step, after unplugging the keyboard,  is to pop the key out using a blunt thin object like a butter knife, simply lever it out gently on both sides.
• The Ornata spacebar, like most, has a metal bar attached to it underneath, and a lever system attaching it to brackets beneath the key. Pop that out too.
• Clean everything using a dry non static cloth, or something like Q20/QD-40, you’ll want to use a small brush to dust out underneath as well.
• Once dried of residue and clean to your satisfaction, it will be clear if anything is physically broken and requires maybe some creative glue techniques to reconstruct. 
• Make sure  the membrane contact in the hole the spacebar goes into is aligned and centred
• Now place the the metal bar back into its slots, and firmly clack it into position, ensuring it is evenly lined up
• Then place the key correctly in position, and push it down firmly all along.

This will most probably resolve your issue, and in fact is something you should do once every 6-12month for all the keys on your keyboard ESPECIALLY if you have pets or are in a dusty area (or have  had neighbours building)

If just cleaning the top part of the key does not resolve your issue, you may have to go as far as completely removing the back as well to totally clean the thing. You can immerse the membrane in soapy water and all the keys (not the board).