Audio Transmit Within A Task - XRDY not being reset.

Greetings, 

I have an audio task where I am transmitting one sample of audio (filling a buffer), at a time. I want to do this for both left and right channels of each MCASP, so I call the following once for each 

while (! ( MCASP0_SRCTL9 & 0x10 ) ); //While XRDY=0

            MCASP0_XBUF9_32BIT = (channel_mask[1]*sinetable[sample] << 15);

I do this for many channels, When I get to the right channel of the MCASP, where the above expressions are repeated, XRDY remains 0, even though I just filled the buffer a moment before. 

This code works well and transmits the audio properly outside of the task, but the moment I enclose it in a task, it hangs when transmitting the second sample. 

I'm working now to instead use an SIO, but any lower level examples, or advice to maintain this syntax would be appreciated. 

Cheers,

Amanda