Here is the solution I have used to remove the stray p tags when using shortcodes in the ACF WYSIWYG (put that in your functions file).
function wpex_clean_shortcodes($content){
$array = array (
'<p>[' => '[',
']</p>' => ']',
']<br />' => ']'
);
$content = strtr($content, $array);
return $content;
}
add_filter('acf_the_content', 'wpex_clean_shortcodes');?>
So far, I have not had any problems with this solution.