Thank you for reporting this issue to our attention.
To help us getting clues and find a solution to this issue, please activate logging on your website, just turn WP_DEBUG to true, by pasting the following code lines in your wp-config.php file, just before the line that says ‘That’s all, stop editing! Happy blogging.’:
// 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 );
More on this in the following topic: Debugging in WordPress.