Hi lukeskymuh, I believe I might be encountering the same issue as you. The flickering I encounter is when the leds are dimmed to a low pwm value, they flicker in a way a candle flame does right before it goes out. Not like a refresh rate problem. I thought it was my hardware but I realize now I am not encountering the problem when I set the pwm to a fixed value, or strobe it with a simple loop. Turns out, the only time I can get this flicker to happen is when running that color swirl code form adafruit which you linked to. We have different hardware setups, but we are using that same bit of code. Do you have the flicker when setting the pwm to a value of 10 or when doing a simple pwm increase loop on the leds?
-Sathi