So using EndierIO't Teleport pad I was able to teleport myself to 10000, 150(Height) 10000, Woot!
I got there and fought the dragon for about five minutes before he killed me. I later go back there to find out no more dragon.

Thankfully I had a copy of my world right before I did that, so I went rolled back, did more general construction, and continued on.

Same thing happened, but this time I didnt roll back :(

I went back, and no guardian to was there, again.

EDIT: On the latest 1.10.2 ver

The guardian is currently very broken in 1.10 and needs a complete re write. I just have not had time to do it yet.

Ah thanks for the info! Ill try not to die on the next encounter. :P