@MojangSupport summoned a wither and went to fight, promptly died after 1/2 wither health. Respawned 200 blocks or so away, went to fight again. Wither was there, healthbar was not! Died 25 more times WITHOUT wither healthbar! It dead now.
Latest version PS4 Pro
Interesting... I would go ahead and report that here: https://bugs.mojang.com/secure/Dashboard.jspa … just in case, so that the developers can see and look into it further. Thanks! ^AS