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_RelatedPostType :: offsetGet( Integer $index )
Gets the post type object at the given numerical array offset, if it exists. Since this overrides offset-get the post type can be obtained by an array-style access directly on the field object – see example.
Note: This method is intended for internal use and should not be called directly.