Some text displays incorrectly (in bright colours) or not at all on Macbook Pro Retina

The text in the image is actually white and say "learn more" but for some reason, it displays like this, and even worse exports like this.

If I select the text, it looks like it should, but as soon as I deselect it, it reverts to the above corruption. (it varies in how corrupted it looks, sometimes it's the whole word, sometimes it's bright green etc) - I've switched off the graphics card in "performance" but it doesn't help.