get_the_content()
returns unfiltered content, and using a shortcode you cannot use the_content()
to return filtered content as you cannot echo inside a shortcode. Your best option here will be is to applying the_content
filters to get_the_content()
, something like:
apply_filters( 'the_content', get_the_content() );
EDIT
Exact usage, replace
$output .= get_the_content();
with
$output .= apply_filters( 'the_content', get_the_content() );