single-{post_type}.php not working

according to your code, your cpt is “event”. You will either need to change the your php to single-event.php or change this line:

register_post_type('event', $args);

to

register_post_type('events', $args); 

Usually they are the plural so the 2nd option is a better choice. With that being said, I always recommend adding namespace to avoid conflicts. Especially in this case because many people have event CPTs.

Try “shc-events” or something like that to make it your own.