Earthsea shape memory - 1 double not changing position

I just took delivery of earthsea. I see one problem with my module - the fourth of the doubles - the one where the second key is to the South-East of the root - is not changing the root when I execute it. Edge triggers, but the previous position CV is output. That’s all. Please advise.

i’ll check this-- it’d be amazing that this wasn’t caught before, but i can understand how this could be an off-by-one error in the code.

My thoughts also but I have double and triple checked, and it is definitely not working as documented.