To set WordPress into debug mode you have to add some entries into wp-config.php. I recommend these settings
define( 'WP_DEBUG', true ); define( 'WP_DEBUG_LOG', true ); define( 'WP_DEBUG_DISPLAY', false );
This will write to a file wp-content/debug.log
Repeat the tasks you have issues with and then examine the log file.
Once finished remember to delete debug.log
For full description see https://wordpress.org/support/article/debugging-in-wordpress/