Conflict between Site Categories and MarketPress

When MarketPress and Site Categories are enabled (only), and you try to assign a subsite to a category in Network Admin -> Subsite WP Admin -> Settings -> Site Category, the following PHP Warning is thrown with every instance of the category selection element:

Warning: Missing argument 2 for MP_Shortcode_Builder::wp_dropdown_cats() in /home/juswri2/justheperson.com/wp-content/plugins/marketpress/includes/admin/class-mp-shortcode-builder.php on line 144

See screenshot: http://storage7.static.itmages.com/i/17/0817/h_1502954556_4832344_cc98298cf7.png

No category can be selected and saved.