Thanks Glen,
The issue I was having was not with the shortcode, but figuring out what the Category ID was. It doesn’t show on the Location Categories page. However, if I select a category and then look at the URL I see “edit-tags.php?action=edit&taxonomy=sm-category&tag_ID=26&post_type=sm-location” and was able to discern the category = 26. Putting this in the shortcode worked for me.
Thanks.