You always need to look at the track record of the team. If they were not producing solid consistent results before you joined them, it's a very good indicator that something's fishy. All that "they are working on something else that we can't tell you" is BS.
If they were, and you were the only one treated like that, hiring you was a decision forced upon the team, so they got rid of you in a rather efficient way.
If they were, and you were the only one treated like that, hiring you was a decision forced upon the team, so they got rid of you in a rather efficient way.