I just installed Jamba for the first time last night, im getting the same problem.

It looks like bliz is blocking auto group accept, or changed some code relating to it. If you turn off 'auto accept group from friends' and the other auto accept invites option above it auto declines all group invites. Just turn all of those ones off, push to chars and you'll be right. You will need to click tho .

[edit]: ah.. fix above.. thx

-Frap