Lucent Singularity locked

I don't have screenshots because I don't know how to take them, but during the second half of a match I played, Lux's Lucent Singularity was completely grayed out and I was unable to use it, similar to how you can't use healing items at full health. I think what might have happened was that I used it right as I died and then when I revived it was on permanent cooldown and stayed that way even after two more deaths. I'm not being petty because we were losing anyway, but it got pretty annoying and I was confused as to how it happened. Is this a common glitch to happen, or am I special?