I had the exact same thing happen to me.
I was playing in Alchemy mode. I was playing on PC.
Opponent had "Authority of Consoles" enchantment in play, so everything was entering tapped.
"Enter" and "Warp" abilities of other cards were working correctly.
I played Astelli for its warp cost of 3, when there was a 3 mana value card in my graveyard to return, and nothing happened.
I tried Astelli again for its full cost when there were several cards at or below that cost, and nothing happened.
I cast Sephiroth, and used his enter ability to sacrifice my wothless Astelli and at least draw a card, but by then then game was lost.
Wow.. I just noticed that this has been an issue since Aug 2nd... that's a while for a rare card to be completely broken.

Note, I was playing in Alchemy mode when this happened, which seems a little buggier than standard so far...

How much mana did you spent to cast it? Did you even cast it? The value of X, and therefore what you can target and return with its trigger, depends on how much mana you've spent to cast it.

Adding log file