Menu levels are large
There are themes, which use autop functions in their content, which means that they add <p> and maybe <br> tags everywhere in the code. You can check this out by looking at the code of your slider, by right clicking on the slider, and Inspect element. If there are empty <p></p> tags in the slider's code, then it must be the case. You can try out to put the Accordion menu's shortcode between [raw][/raw] tags like this:
[raw]Here comes the Accordion Menu shortcode[/raw]
because in some themes this works. If it doesn't, in most cases you can remove this from your theme by adding this code into the first line of your header.php file:
<?php remove_filter( 'the_content' 'wpautop' ); ?>
But if you would like to keep it, and the [raw][/raw] doesn't work, then you should contact your theme developers, and ask them, how can you put a shortcode into a page or post without autop formatting.