You may need to cut back on his pellets to make him eat hay. And maybe even cut back on his greens. Hopefully, if he gets hungry enough he will eat the hay. You said that you had tried a few different varieties, but what about some different brands? There may be some brands that are more appealing to him. American Pet Diner Timothy Gold, is a second cutting and it’s softer and fragrant. Small Pet Select also has nice hay. Oxbow makes an organic meadow hay that my bunnies really like. The Binky Bunny store sells their own brands and they have some nice mixes as well as one variety bales of hay. I’ve never seen blue grass sold anywhere else. There are also hay toppers with dried herbs and flowers that you sprinkle on to encourage eating. Binky Bunny sells that too, but I see that they are sold out right now.
Make sure that your bunny doesn’t have any teeth problems. Those can prevent rabbits from eating certain foods.
I hope that he will come around and start eating at least a little hay.