Doesn’t honor single-{$post_type}.php override

I’m trying to customize make a custom post-type template. After creating the custom post type name site_content, I copied the stock content-single.php to single-site_content.php. I made some edits to the single-site_content.php and saved and uploaded. The edits I made didn’t show up. I then tried renaming the custom time to content-single-site_content.php and that didn’t help either.

Environment:
Wordpress 5.7.5
Modern Storytelling 1.1