Rendering problem

Hi, I have made a logo design in Illustrator. I have imported this EPS file into Swift (I also noticed that you can only import text when it has been converted to outlines) where I have animated it. The logo is basically 3 layers, each a different colour. After rendering, I get a flickering of pixels when the animation is playing. I have 2 lights on the text…certain pixels seem to turn black at the same point every time. Why is this?

Thanks in advance,