Expanding custom fields in PowerBI into useable data

I have a portfolio of projects and I need to create a dashboard using custom field data from the individual projects (I have about 30 customs fields). I have pulled the data into Power BI and expanded the customs field information. I then go to pivot column to get the custom fields into rows. This is where the issue occurs. I have a flattening problem where by each data element is on a different row so for 4 tasks rather than 4 rows I’m getting 30+ rows which means I cant build the dashboards I need. Any ideas how to sort? Have tried Asana support who say its not their problem as it should appear as I want it too.