I have text that I am trying to turn into a opacity mask, but when I do the image that I am masking turns into grayscale. Any ideas why?
Your mask is the wrong way around!
You're masking the text with the image, not masking the image with the text. The image is obviously converted to grayscale to be used as a mask and the text is black—so, the result is obviously grayscale.
Simply do the same as you're doing but with the text on top of the image (the mask needs to be the top object when creating your opacity mask).