Array formula working in one workbook but not another

Hi All

I wasn't sure if I needed a new post or if I should continue the original?
But I think this is a different issue, so figured it was best to start a new topic (apologies if that was not correct)

Yesterday CARACALLA gave me an amazing formula to count distinct values in a range, excluding blank cells or cells where values begin with '#'
Original post here

It works great in the dummy data doc I uploaded called Book1.xlsx

But I can't get it working in my 'Clients Workbook' and I'd be super grateful if anyone can see where I'm going wrong.

It's throwing errors about a circular ref but I have no idea why?

Any help would be appreciated
All the best
Vicky