We're having the same issue and submitted a Customer Care ticket.

Hello, Thank you both for your inputs. I have not thought leveraging the flow report with the marketing channel dimensions so I will give a try with that.

Hi @jkm-disco, I've just tried to replicate what you recommended and I'm not seeing the expected results : Issue #1 :Two rules have been created as you can see below : When I used the "Rule set tester", it returned a good result : Issue #2 : When I activated the rule then went to the dimensions that has been classified, I only saw "unspecified". Did I do something wrong here? Another question regarding your response for the part two please : We have ~500K unique values for this dimension, creati...

Thanks a lot Andrey ! (Happy that I received an answer from an AA rockstar)