glow effect on signs glitch

Glow effect on signs glitch

What I expected to happen was...:
when adding text to a sign, add the glow effect by using the glow ink sac, the text. the text should glow

What actually happened was...:
when adding text to a sign it is clear. once the glow effect is added by using the glow ink sac, the text glitches and cannot be read. 

Steps to Reproduce:
1. place sign
2. type the text to show on the sign and press done.
3. add color to the sign (optional and does not affect clarity)

4. add glow effect to sign, (text glitches)

5. if you add black ink, glow effect is removed and clarity returns.