Masterpress 1.3.6 is a compatibility release. It resolves an edge case with shared fieldsets not working for MySQL 8 when the fieldset is limited to more than 1 post type or taxonomy or excluding any post types or taxonomies.
MPFT :: __toString()
Note: many field types will overload this method to allow different types to output more appropriate HTML code. For example, the image type will output an image tag (which is more useful than the URL which is stored), and the Visual Editor type will run the WordPress content filters over the content of the field.
This method is not intended to be called directly.