Hello @JackieX I just wanted to assist you further and confirm what the other forum members have advised you. The new hidden review system has not yet been launched and we will let members know when it goes live.
It sounds like you were seeing the newish pop-up prompt on your dashboard which opens as a box with the stars at the top, if you cross out of that box then you can go to your drop-down menu and select ‘past sits’ this will take you to where you can view your recent review and leave your feedback.
I can see in this case you have successfully managed to leave feedback for the owner. Congratulations on your review 
Feel free to DM me with any questions.