1591 contacts in the list...

Gets down to 129 with segment 

CONTACT EMAIL AreaOfInterest doesn't contain ' none '

AND Country contains 'countryA,countryB '

AND Company Name doesn't contain ' CompanyA,CompanyB,CompanyC '

(same issue with "isn't" by the way).

958 with segment

CONTACT EMAIL AreaOfInterest doesn't contain ' none '

AND Country contains  'countryA,countryB '

Obviously there isn't 829 people from just three companies, so what is going on here ?

Apparently we have a Company Name field and a (custom) Company field. Segment above works with the  Company field (948 contacts).

But why doesn't it work with Company Name, no matter what is in Company Name ?