Hi Jensen,
I posted looking for help with my WS2812Bs here not long ago. Still looking for help but you may find something useful in my post. Your last comment indicates you are using 3.3v for power to the pixels if I understand you correctly. I think these are rated for 5V. They might work ok at 3 but a lot dimmer and likely not full 8 bit resolution. You can get away with using the 3.3V GPIO to provide data even with 5V led power. I use a 200 Ohm or so resistor in series with gpio pin and if you like a pair of switching diodes to 3.3v rail and ground on the controller side of the resistor to keep ringing in check. Better if the diodes switch fast than handle more current since there is very little current involved. This is not like driving a relay coil.
Q