The first time this bug happened, my brother (playing from an ipad using cross platform multiplayer) and me created a new world to kill the ender dragon(getting stuff from creative, then switch to survival). in the end, i died once, but my brother was still alive(which is fine). i then go through the portal again, but at the end, the dragon's health is not shown, although she is there. 

Issue: dragon's health is not shown after dying in cross-platform play

How to start it(may not happen for everyone:

1. go to the end with a friend on cross-platform play
2. die in the end(only you, your friend needs to be there)
3. come back. now the dragon's health is not shown

this only happens when i am doing cross-platform multiplayer. after the first issue, i went to fight the ender dragon myself, and that time the health was shown(even after dying). this happened twice, which makes me believe it's a bug. sorry i forgot to take a screenshot