Phantoms don't dive properly

Samsung Galaxy J7 Sky Pro

So I downloaded the beta just today to see if the missing limbs bug was fixed- it is. So, I started up a world, and decided to wait for phantoms to spawn so I could farm their membranes. But, once one did spawn, it never came down to attack me, and ended up dying when day came. It seems the AI is a bit bugged, as it'll dive down a few blocks, and then stop, as if it hit the ground, and then fly back up. I decided to climb up a nearby mountain to kill it that way  which only resulted in the phantom flying higher in the sky, and continuing it's glitchy behavior. 

(also, this time I actually did a search for the issue, and nothing related popped up. So yeah.)