Multi word tags

Hi, I was wondering if I’m doing something wrong – if I’m trying to load all items with the tag ‘foo bar’, using the following shortcode:
[ajax_load_more posts_per_page=”6″ tag=”foo bar” button_label=”More Tagged” max_pages=”50″]
it doesn’t seem to be pulling any results. However, it works fine for all single word tags. Any ideas?
Thanks

https://wordpress.org/plugins/ajax-load-more/