Apparently there's a glitch (yes, another one, anyone surprised?) that's keeping April scores that were withheld and then released from being transmitted. You have to call AMCAS and ask (probably had better demand, and speak to a supervisor, not a "specialist") for them to send a letter to your schools with the AMCAS scores. Apparently they know it's happening, but aren't doing anything about it unless someone calls and complains. I would also send a copy of the score report you got to all the schools with a cover letter explaining the situation.
See the thread entitled "You are Not Going to Believe This" for more details and suggestions.