Please refer to attached screenshot, what does it mean? I have a custom field 'materials' already been used for one Post Type 'Course', now I want to assign this to another Post Type 'classs', each course will have 1-to-many classes, so that when I assign several classes to a course, each class can quickly be inherited all materials from the course and also can have its individual materials.
Hello. Thank you for contacting the Toolset support.
As you can see the message the custom field group where you are trying to assign the "materials" field should be using the repeating field group and when the custom field group is holding the repeating field group - you can not assign that custom field group to another post type.
What if you try to create another custom field group and try to add the custom field "materials" field to this custom field group and set this custom field to display with the post type you want.