Thank you for contacting Blizzard Customer Support. We are currently investigating similiar such reports. Do try to perform the vote kick while in town and see if that doesn't help. Otherwise, please do continue to be patient as we will do our best to resolve any issues related to the feature.
That was a few days ago and I just joined a group with an AFK player so I had a chance to test it. From my one test so far, the work around in the quote only partially works.
I joined a public game and one guy was just sitting in town doing nothing. He ported to us and helped for a few seconds and then went back to town to just stand by the WP. At first, 'vote kick' was grayed out. It said the feature is only available in public games, but I joined the group with the public game feature, so it had to be public. It also said the feature is disabled for people who abuse it. I don't see how it's possible that I could be abusing the feature. Even when I have tried to vote kick, I haven't been able to due to the difficulties described in the original OP. Going to town didn't change this at all.
I checked a few minutes later and 'vote kick' was white, but I still couldn't use it in the dungeon. Clicking it did nothing. But going to town DID work and the kick was successful. So it's not completely broken, but it's far more tedious to use than it should be.
So what changed in this case? Why did it go from gray to white? Was the game incorrectly labeled as a private game at first instead of a public game? Or are players being incorrectly labeled as "abusing" the system? Even if a player has a history of vote kicking too much, they should still be able to kick someone who's been AFK for 10+ minutes.
I'm sure other people have mentioned this, but I feel I need to bring it up again since it's still a very annoying issue.
I've been in many 4 player games where 1 player is sitting in town for 10+ minutes and the other 3 can't kick him. Either 'vote kick' is grayed out or it's white, but clicking it does absolutely nothing. Other players in the group say they try to vote kick and well, but get the same thing.
I completely understand the issue with needing to restrict vote kicking. It's not good for the community to have players kicking each other for stupid reasons. But it's not good for the community either when games are pointless made harder because of an AFK player. One way to solve this is if a player doesn't press any buttons for 10 minutes, then any player can initiate a vote kick, even if they have a history of vote kicking.
Seriously, why hasn't this been fixed yet? It seems like something that could be solved with a hotfix.