“Mammoth Jalapeno” stopped growing (Hydroponics set up)

Hey so this is my first attempt at growing mammoth jalapenos in a hydroponics tower I have made.

My problem is that the biggest ones seem to have stopped growing for the last 30-50 days now, but really they should be bigger by an inch or 2 and turn red when it's fully grown

So I'm wondering is if I don't actually have mammoth jalapeno seeds, if they don't always turn red, maybe my set up is wrong, or do I need to wait longer

Jalapeno in picture is around 2cm wide and 7cm long, it's the first one the plant has produced

Plant is indoors so room temperature can vary from 16-22°c (I imagine is hotter in the corner with the grow light)

Phone lux sensor is saying it's getting beween 5000-8000 lux consistently for 12 hours a day

Currently have 6 plants in the tower, 3 on the lower level and 3 on mid level