xpand2 loses sound

[Ryanb978]

Hi I'm new to protools, this is my first post. I have a 2011 macbook pro operating system is yosemite. If i make a new instrument track and use xpand2 it will work fine for about 15 seconds then all the noise from the selected plug in stops, it still makes some noise but doesn't go above a very low point in the velocity bar on the side. It was working fine last night but when I opened it today one of the tracks was in grey(not muted, i could toggle the mute still no noise) and when i tried to rerecord this started happening. Anyone know what the cause of this is/how to fix it? Thanks