Here are some things I would try:

When she does run, SMACK HER in the rump with the halter. Chase her off from you. You want her to understand that running is NOT a desired response. Take a lunge whip if you need to and get after her! I know this sound contrary, but trust me, it works . (I have had a few "runners" and it always works!)

When you do catch her, even if you had to chase her down, give her some treats and love! Make a big deal that she let you halter her. Then, lead her out of the pasture, give her some grain, brush her, give her some more treats, then turn her back out.

The next few times you go to get her, don't ride or work, just have some "fun". Walk her around, let her graze, groom her, bathe her, give her some treats, etc.

Next, check your saddle fit. Sometimes horses will be "good" undersaddle, but still be in some pain. It's always good to double check, even if you think your saddle fits fine. Put it up there without a pad and check the fit thoroughly.