There are dozens of reports from upset Google Maps Transit users around the States that the directions are simply not working.
Like I said, several of the threads are at Google Maps Help forums where users are reporting issues in Philadelphia, Baltimore, Orange County, Cleveland, San Antonio, San Antonio and many more locations.
Googler, Ryan Kelly from the Google Transit team is responding to these issues. He said:
Appreciate your reports; I'm looking into the agency data now.
Some are already fixed while others still need repair. I am not sure if it is on the agency side or on Google's side but I suspect a feed format change happened and many agencies did not update.