I have Deadlock and am able to invite people, if someone wants an invite just comment with your Steam URL (or DM me) and I will send invites out later today to you.
Similarly, if there are others out there who want to share invites please feel free to comment your Steam URL (or whatever).
GLHF!
PS, if I've added you as a friend but you've not heard from me please feel free to message me on Steam or leave a comment on my profile and I'll invite you ASAP.
I don't think that was ever a thing. I wonder what started that.