Hi, might be I'm doing something wrong, but I recently upgraded to Mongoid 8.1 and converted Symbol fields to StringifiedSymbol and it seems querying by embedded StringifiedSymbol field does not work:

Model.find('...').embedded_relation.map(&:file_type)

=> [:pdf, :pdf, :pdf]

Model.find('...').embedded_relation.where(file_type: :pdf).count

=> 0

Model.find('...').embedded_relation.where(file_type: 'pdf').count

=> 0

Model.where('embedded_relation.file_type': :pdf, id: '...').first

=> # document found