Endermen in daylight do not freeze when looked at, do not stay angry

Enderman in daylight (in plains biome). I looked at him, walked up to him, hit him with a sword. He teleported away and became non-angry. Looking at him again, which supposedly freezes them in place until you look away, he kept teleporting away before I could even catch up with him again. And after each teleport he went back to peaceful again, even though the 'angry enderman' sounds continued to play.