“Please select some product options before adding this product to your cart.”

Good afternoon.

I am getting the subject message whenever I try and add a variable product to the basket even though all product options have been selected. Here is an example of a product on my website that it is happening to: https://hwbmobility.co.uk/product/haddon-adjustable-bed/. Simple products are not affected.

Any help would be greatly appreciated.

Best wishes

Andrew