American Pit-Mix needs good home

This is Bailey and she needs a good home where she is the only dog.  She just turned 4.  She does well in her kennel, loves to take walks on the leash but doesn't usually stop once she gets going.  She is potty trained and will not go in the house at all. She is so playful and is fun to watch when she gets the zoomies. 
She loves people and she gets along with one of our two other dogs, so why do we need to rehome?  We cannot keep her for the safety of the other dog she is not friends with - she reacts to the nipping instinct of the blue heeler we have.  She is not aggressive, but she loves to give kisses and jump on you, loves to cuddle and play.  We ran her DNA and this is her compilation:  57%American Pit Bull Terrier, 36% American Staffordshire Terrier, 3% Bulldog, 2% Boxer, 1% American Bulldog, 1% Boston Terrier.