Facing away from signs with glowing text makes the text disappear or z-fight

Steps to reproduce this issue:
1. Place down a sign
2. Write some text on it
3. Dye it (optional)
4. Right-click the sign to make the text glow with a Glow Ink Sac
5. Slightly face another direction so that the text disappears/z-fights

Video demonstration of the bug (YouTube)

Notice how the text disappears and/or z-fights when you're not directly looking at the sign?