When you spawn the wither it moved around very quickly then quickly ascended and was no able to kill without an elytra.
Comments 3
Could not reproduce, in my game it hovers close to the ground so the player can damage it easily by arrows or sometimes even by sword. Can you upload a video, if the issue still reproduces?
Cleaning up old tickets: This ticket had been set to 'Awaiting Response', but has not received a response from the reporter (~3 months+) so is being closed as Incomplete. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.
For any account or purchasing related issues, please contact Minecraft Customer Support directly, as we cannot assist with those here at the bug tracker.
Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki
In 1.16.201 seems to float above the ground only before half-health (suitable for bow&arrow), thereafter goes close enough to the ground for consistent sword action.