Hi!
Apparently you have a "purple" led light. The problem with this kind of lighting is you only have one thin spectrum of red and one thin spectrum of blue.
But your plants also need the "other" blue, red, orange, yellow and green (less than other color but green is needed anyway) wavelengths.
Because of that, this kind of light must be used in addition to a more generic lighting, who can cover larger spectrum.
For now, you could add white LEDs in you grow room, but for your next grows, I encourage you to switch to another model (or if you're confident with an iron, you can switch actual COBs to full spectrum ones).