Status:
1. There are other issues with the API at the moment. The problem has started happening right when the other API issues started about 7 hours ago, but the other issues were resolved and this one didn't.
2. So this is a general problem (on facebook side). Other apps have the same problem.
3. There is a bug for this in facebook bug tracker:
bugs.developers.facebook.com/show_bug.cgi?id=9046
4. I have tested with an (infinite) session: This has worked on my test system. So I suggest the problem is that the stream_publish function does now require a session (also when offline_access is granted). - LOL
I can change AutoTweet for usage with an (infinite) session key. But this is much work for me and also users has more work to do when enabling facebook for AutoTweet.
So I will wait first for an answer from the facebook developers...
Ulli