Did they get rid of the star ratings system in 2.2? Old reviews show up with star ratings but when creating a new review, star rating isn't an option, just a place to write a text review.
I've not seen any news that this functionality was removed. The code for ratings is still in the template: https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Review/view/frontend/templates...
Are ratings still set up in admin?
Are you using a custom theme? Perhaps changing back to luma theme temporarily will help to identify if it's a theme issue.
It requires makeing sure the Rating Visibility is set. Go to Stores > Attributes > Rating you should see three ratings, edit each showing the correct view for your store then save.