I have created a design in Sketch and exported it as an .svg. I then opened that .svg in Illustrator to make a few edits. I need to change the fill color of a icon that is an .svg. But I am unable too... I had the .svg red in Sketch, but when I exported the design as an .svg the icons became black.
It seems as though your objects have a mask applied / was traced.
What you would need to do is just click on
Expand on the top of your screen.
It should then become regular vector shapes, with which the color can then easily be changed.
You have to expand the SVG and select it, then you will be able to change the color.