Odd reference behavior

I have the following mapping:

public class Research : BaseEntity

        public long Id { get; set; }

        public long PrimaryImageId { get; set; }

        public ProfileImageEntity PrimaryImage { get; set; }

When I query from the database using LoadSelect.
The PrimaryImageId is correct. but PrimaryImage has different value. with other id.

I have only one place where I set PrimaryImageId and zero places where I set PrimaryImage

How can those values be different (different id)?

Please provide a stand-alone repro I can run locally to repro the issue, you can create a runnable example on Gistlyn otherwise full source code or a link to a GitHub project would also suffice.