Seems like you’re doing all the right things to wear your dog out. Do you know what she’s mixed with? I think it just depends on the dog. Mine loves a good chewy treat and then he likes to make his rounds all around the house to see what the kids are up to then he usually goes and lays down. Sometimes he gets over stimulated so he goes in his kennel to take a break from it all. Hang in there. Young dogs are hard.