I'm just getting into the world of SAGE development and at the same time, I'm using the Advanced Custom Fields plugin.
Let's say, that we have created two custom post types (Professors, Lessons). Each post type has its own custom fields. At some point, however, I would like to add a new custom field to the Professors' post type that will be called Lessons and will be a selectable list of all the lessons that one created in the Lessons post type. So In that way, you can connect each professor with the corresponding lessons of his/hers.
So far I couldn't find a way to pre-fill/pre-define a custom select field with values taken from the database (e.g post titles). Is there a different way to achieve this?