SO I have a WS2811 LED strip.
I have connected the 12V to a 12V source, Ground to Arduino. Data through a 220Ohm Res.
When the strip goes is set to "Black" the Red and green Leds come on.
If I set the whole strip to Red and incrementally set the pixels to black, the red and green come on dim to start with and get brighter as the other pixels are set to black.
I have experience with ws2812b but not these!
Also what are your circuits you are using for ws2811?