It is saying that brand cannot be a list of brand.
Actually, the problem is each email is associated with a single brand but in a groups (as the name suggest) we have multiple brands so that field is a list of item.
Not able to understand how to solve this for showing all emails from brands who are part of that group.
Your brand field is a list of Brands but you’re using the equals operator (=) in your constraint which is a singular operator.
without knowing what you’re trying to do, I can’t give much specific help…
But either you need to change your search constraint, or change your database structure.
(But I’m guessing you’re trying to find emails who’s Brand is in the current page Group’s list of Brands… in which case change your search constraint to that).