If I go to my teams page in BAM! I'm told that I'm no team member of SETI.Germany in some projects, but that's wrong.
The projects I'm talking about I'm even the founder of S.G:

Why is this so?

I think the problem is BAM doesn't know you are a member of a team at those projects because you joined on the project website. If you tell BAM to go ahead and have you join the team on those projects it will be happy.

Note joining teams from BAM did not work with WCG and Climate Prediction the last time I tried.

I joined not a single team via BAM! I usually created the accounts at the projects, because I was a member before they were included in BAM!
It works for nearly all projects, and would try to join the team I'm already in, if it wouldn't be for me being the founder in that projects.

Some projects had problems last weekend when the team member/founder update script ran (like Freehal and nQueens, maybe others). The returned invalid results which my script did not anticipate (now it does).

When the projects are back to normal operation your team membership should return to normal. Since this script uses many resources (it checks all users at all projects, each user with its own RPC call) it only runs once a week, Sunday night (GMT).