I have created a custom entity that links existing employees with projects they completed when they were not with our company (outside experience). These projects contain (among other fields) a lookup for employee and a subrid for a many-to-many relationship with another entity called markets (the classification of the project as many projects fall into many categories - this is used also with our historical projects entity as well as others). This solution works without incident on our test environment but throws an error when I import to production. The error appears to be on the project to market relationship with the notes "Attributeid is null."
Error log below. Has anyone run into this before? Thanks