Recommendations Criteria Not Showing Up When Building Activity

Hi! I am trying to create a recommendations activity to show recommended articles on a blog based on the article a visitor is currently on. My criteria is to look at the current category ID and show other articles w/ same category. I believe the best way to set this up would be an items with similar attributes algo, with current item as recommendation key and the content similarity using entity.category. When I create the activity, I am unable to find/select that criteria I created. In fact, out of the 59 criterias I have, I can only see 26 within the activity even though I've made sure the activity and criteria both use the article and category page types. Please assist, thanks!