Regarding mbox categoryId entity attribute

Hi,

When I pass product information to Adobe Target via mbox, I was sending multiple values in comma separated fashion with categoryId entity attribute like 'entity.categoryId=Test Category Id1,Test Category Id2,Test Category Id3'. And when I see the product in Recommendations Premium product catalog, I found that it took everything as one category ('Test Category Id1,Test Category Id2,Test Category Id3') instead of segregating into multiple categories by taking comma as a delimiter ('Test Category Id1', 'Test Category Id2', 'Test Category Id3'). It used to work fine in Recommendations classic but not in Recommendations Premium. Can anyone pls help me out here?