M2M relation junction table displays NaN instead of fields

[Rick Wouters]

1. When creating a junction table with the following configuration:
   
   The items in the junction table are displayed as follows:
   
   While I would like to be able to display fields of the relationships(partner.name for example).

2. Create a M2M according to the guide in the docs, assign items to it and watch the result.

3. I am using Directus 8.7.1, an SQL database on a shared host. This error occurs in all browsers.