Nebula signature ability broken?

LightYagami85

...or how does it work?
Once my Nebula lost both Self-Repair charges signature ability says:
"When Nebula is out of Self-Repair charges, she tries to recalibrate her implants, granting her a 80.18% chance to regain a charge every 10 seconds."
(Source: https://playcontestofchampions.com/champion-spotlight-nebula/)

But she doesn't regain any charges ever again after both are lost. No matter how long the fight takes. Happening with the 3* and the 4* version of her.
Maybe someone can help me and tell me how it works, but in my opinion it's broken. Or maybe it's just been bad luck.

ZzyzxGuy

I think you may have just been really, really unlucky. My 4* Neb gains her charges back.