Using ACF with MailPoet Newsletters

[ Moved to the Fixing WordPress sub-forum. ]

Hey Guys,

I am trying to get a fix to use my ACF fields in MailPoet to be sent out in my newsletters. I am trying the approach by hooking into the_content and filtering in my data that way but it comes up blank and does not show anything. Does anyone have any ideas on how this can work?

My code is:

add_filter( 'the_content', 'acf_content',1 );
function acf_content( $content ) {
    if ( is_singular( 'new-tips' ) ) {
        $content = get_template_part('template-parts/content','main-tip');
    }
    return $content;
}