I have the same problem too. I played one match of Garden Ops more than a month ago and haven't felt the need to play it again since (this was after the Taco DLC. I Remember because it installed it along with the game initially). About 2 weeks ago, I discovered I was unable to play Garden Ops.
I try to join a friend's invite, it sends them to the dashboard and me to the Garden Ops sub-menu. I try to join random, it just sends me back to the Garden Ops sub-menu (no idea what happens to the players I tried to join). Host my own, nobody joins. Friends try to join via invitation, sends them to Garden Ops sub-menu and dashboards me. Also doesn't let me restart the game for a minute or so.
The strangest thing is that I found out I can play solo. I would have little problem with this except I enjoy achievement hunting and some of the achievements are impossible to do solo (CRAZY mode, anyone?).
Anyways, I just want to try and play this with friends. Because that's what makes the game fun. And it really sucks to have so much missing when I expected the full, working product I initially paid for.
