You just have not left her tied long enough. Just tie her until she 'gives it up'. It may take one day or 3 days, but they all give it up. Tie her in a safe place in the shade (under a tree is ideal) and leave her alone. Do not leave her is cross ties. A trail hors`e does not need to be cross tied -- ever and you cannot safely leave one.
Tie her in the morning, offer her water at noon (but do not be alarmed if she does not drink all day), put her out at night and tie her up again early the next morning. Do this until she stands still when you first tie her out.
I just went through this with a 7 year old QH gelding. He stood for 6 hours the first day before he stopped screaming and pawing. I put him back out. The next day he screamed and pawed for 3 hours. I fed him and put him out. Yesterday he called out twice, never pawed and was resting a hind foot within 5 minutes. We are over it and ready to go to work now.
We get all of our trail horses broke to tie indefinitely. It is nothing to tie them overnight or for 10 or 12 hours at a time. They all just go sleep with a hind foot rested when tied.
Be sure you tie a horse to a place that is safe. I prefer a nylon rope hanging down from a tree limb. Always tie a horse shoulder to wither high. Never tie them where they can get their heads lower than their shoulder. Always tie with a big swivel snap fastening the rope to the flat nylon web halter. NEVER, NEVER tie to a tree limb with a halter and lead made together. The rope will twist up (because there is no swivel) and can hang the horse.
I prefer the tree limb because the horse cannot paw anything or bang its legs and feet on anything. They can go around and around (which they all will) and they will decide to give it up. Then they are done with it.