When opening up a lineart image that I would like to color, it is automatically set to grayscale, and will not let me select any colors. I've tried color on a new layer, as well as checking show colorspace selector. Showing color space selector gives me color in the advanced color selector tab, but they still color in gray-scale on the image. Is there a way to allow using the full palette on a grayscale image, or better yet, a way to open it not as grayscale?

I guess you opened a grayscale image. You can check by looking on the string in the statusbar. If it says something about grayscale, then the colorspace of the image is grayscale.

To fix that go to menu Image->Convert Image Colorspace... and select RGB.

Hi Carterhill

it seems that your line art file is in greyscale color profile.

you can convert the color profile of entire image from grey scale to rgb ( or what ever you require) bye going to

Image menu > Convert image color space.
then select RGB from the dropdown and choose suitable color profile ( ideally sRGB-elle-V2-srgbtrc.icc)
then press ok.

hope it helps