Hydros X2 breaks Collective - not able to add

Hi,
I am in the UK. I bought Hydros items from Premium Aquatics. I have the X4 and Wave Engine working as a Collective. All three are powered by the Wave Engine with two command bus cables. I have two terminators one at each end. It does not matter what order I place the X2 into the collective - first, last, or middle into the collective - the Collective breaks. Also whether the X2 is between Wave Engine and X4 or after the X4 in terms of cable sequence.

I have updated all three devices successfully to firmware 192 prior to adding to Collective.

I have now run out of ideas why the X2 will not add to the collective. As I am in the UK could give me some guidance if can get fixed in the UK = PCB repair to otherwise. Are the command bus PINS correct on this X2? I do not think my command bus cables are faulty as either work in forming the collective between X4 and Wave Engine.