The 4 Corners ABC documentary went into this. Just double checked and it says Inmarsat privately handed over the data to it's distributor on the 11th March, who in turn passed it to Malaysia.
However, Hishamuddin dismissed the possibility that the plane continued to fly on the 13th March. He actually made a point to dismiss it. It was another two days before they abandoned the search in the South China Sea.
My money would be on poor communication and incompetence on the part of Malaysia and Hishamuddin's ever present foot-in-mouth syndrome..