"The End" dragons are almost invincible

[Bummer3]

Repost from discord #technical-support since no-one replied to me on discord and i wasn't sure if this was being looked into. Sorry on my behalf if this isn't the case.
Note: ss=screenshot

Hi there we have a problem on Oceanblock with both the ender dragon and the chaos dragon. I've put a ss so you can see for yourself. So the problem is that our hits won't recognize because it says "waiting for server". Now for the normal ender dragon it's quite alright as when it floats still above the fountain we are able to hit it because... well its standing still. But for the chaos dragon it's almost impossible to kill since the mechanics are way different and it pretty much has "waiting for server" at all times. We tried killing it for an hour and gave up since we could only land 3 hits. I hope there is a way to fix this else we cant upgrade to chaos tier.

Now i know that i mentioned the "waiting for server" a lot but this might not be the real issue, it might be some lag between the dragons moving and the hitboxes of some sort. The hitboxes on these dragons are quite large and with a staff that does ~300a-dmg it would be very noticeable if you hit it or not. So why am i saying that the HUD toolbar might be wrong? So some of the mekanism stuff actually also shows this error but they work quite fine as is. The next thing is that the normal enderdragon still shows this while being still on top of the fountain as shown in one of the ss's. 

As we don't know the issue 100% i cant really put much more detail on it for now. If you want different proof like a video or some sorts i will happily make one.