show shortcode instead of HTML

@duckian – If this CPT is using a custom template sounds like it is calling get_the_content rather than the_content. The difference is that the_content applies do_shortcode which is responsible for rendering the shortcodes. If that isn’t happening for shortcodes in that CPT then it is the most likely place to look. Try it on a page / post and see what happens there.

Hope that helps.