Do you see any errors in the browser console when trying to bulk select those items?
Can you please test minimal, using a default theme(if possible) and with all non-Toolset and essentials plugins disabled to see if the error persists. If possible make a backup of the site before doing it or test on a staging copy.
In addition to that, I'd like your help enabling the debug mode to help us track the error down, please add the following code to the wp-config.php file:
// Enable WP_DEBUG mode
define( 'WP_DEBUG', true );
// Enable Debug logging to the /wp-content/debug.log file
define( 'WP_DEBUG_LOG', true );
// Disable display of errors and warnings
define( 'WP_DEBUG_DISPLAY', false );
@ini_set( 'display_errors', 0 );
// Use dev versions of core JS and CSS files (only needed if you are modifying these core files)
define( 'SCRIPT_DEBUG', true );
