Creating Case Reports in Power BI


We have recently set up an ODBC connection to Power BI to create reports using data form Create. I have created an ODBC database with views to a number of data objects for a case type and imported the data into Power BI successfully. However, once in Power BI we are having trouble creating joins between the data objects. In the views I have selected the relationship fields to the different objects in Create and when trying to create a join using these relationships the only relationship type BI will accept is many to many. Has anyone come across this before and figured out a way to resolve it?