Hey there.
I've found a conflict with a popular plugin, Mashsharer:
https://wordpress.org/plugins/mashsharer/
Mashsharer gives me an error message on the edit screen:
Fatal error: Uncaught TypeError: Argument 1 passed to MB_Tabs::opening_div() must be an instance of RW_Meta_Box, instance of MASHSB_RW_Meta_Box given, called in /home/run4ac/public_html/wp-includes/class-wp-hook.php on line 286 and defined in /home/run4ac/public_html/wp-content/plugins/meta-box-tabs/meta-box-tabs.php:73 Stack trace: #0 /home/run4ac/public_html/wp-includes/class-wp-hook.php(286): MB_Tabs->opening_div(Object(MASHSB_RW_Meta_Box)) #1 /home/run4ac/public_html/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters('', Array) #2 /home/run4ac/public_html/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #3 /home/run4ac/public_html/wp-content/plugins/mashsharer/includes/admin/meta-box/inc/meta-box.php(216): do_action('rwmb_before', Object(MASHSB_RW_Meta_Box)) #4 /home/run4ac/public_html/wp-admin/includes/template.php(1073): MASHSB_RW_Meta_Box->show(Object(WP_Post), Array) #5 /home/run4ac/public_html/wp-admin/edit-form-advanced.php(714): do_meta_boxes(Object(WP_Screen), 'normal', Object(WP_Post)) #6 /home/ in /home/run4ac/public_html/wp-content/plugins/meta-box-tabs/meta-box-tabs.php on line 73
Any help would be great tx.