I think that your Great Pyr is ignoring commands like that they are super smart if there is a mutal respect theyll work with you.
Try talking to your gp like you would a human. Ive found out simple commands are just ignorned like you and I would ignore a simple command lol.

Maybe throw in a treat but its been my experience if you underestimate their intellegence and treat them like a lab or other dogs you wont get anywhere.
Thats what worked with mine at least maybe it will be of some help to you wish you the best of luck Great pyr arnt a easy breed to work with hope it goes better for you with yours