when using /summon EnderDragon it wont show its boss bar and it seems to act odd, like it will stay still then start moving foward.
https://www.youtube.com/watch?v=D9GPSc_Q_Ts&feature=youtu.be
a video to show what i mean. (ignore the last little bit i forgot i was updating a driver)
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Not a duplicate of MC-83239
Duplicate of MC-82911 - not fixed.