The Likely Open to New Roles filter is only available to users on Enterprise level plans.
The filter Likely Open to New Roles uses a machine learning algorithm to predict which candidates are most likely to change jobs within the next 12 months. These candidates have not explicitly indicated they are looking to move, but their profiles show patterns similar to others who have ended up moving.
Check the box next to More likely to switch to activate the filter. If you don't see the filter on your searchpage, click View All Filters and add the filter to your list.