The problem is entirely with Avatar Press circling the drains. Its a dead company that knows its dead but is shambling on.
Gillen's words from January:>To put it bluntly: I can no sooner choose to publish issue 18 of Uber Invasion than I could issue 21 of my Uncanny X-men run. >It’s WFH. I do not own it. I cannot make any decision like this about it.>If it was in my power, I would have found a way to publish it. It’s only 4 issues left. I hate leaving things unfinished. Hell, even if I didn’t, I’d likely have done it just to stop having random “What about Uber?” questions turn up in my social media presence. >Conversations are ongoing (if slow) with Avatar about what’s happening, as they have a lot of ducks to get in a line, but any question about Uber’s publishing can only really be answered by them and - as I have said many times before - as soon as I have any actual news, I’d share it with you.>I understand your frustration, and I wish I could say something else more solid, but I’ve got nothing more solid to say.
Apparently Avatar is publishing some comics again, so who knows, maybe they'll greenlight the final four issues.