Guys, I spent a long time trying to get the NeoPixels to behave using a Raspberry Pi. It's really tricky.
Read through the multiple walk-throughs on Adafruit regarding the NeoPixel + Raspberry combination.
"Note that you might be able to get your NeoPixels to work without any level conversion, but it's not really guaranteed because the data line needs to be at least 0.7 * VDD (5 volts), or about 3.5 volts. Try one of the level conversion options below if you can't directly drive the pixels from your Raspberry Pi."
So if your Raspberry Pi has peripherals and is loaded down, the internally-available 5V may be slightly less. So if you ever see an undervoltage condition then give up trying to do NeoPixels without a level converter in place. I personally tried the diode-only version and I did not have success with that. And I used a 10A 5V switching power supply for the 60 LED ring and still this was problematic. I have purchased several of the logic level converters but I haven't returned to this project in a while.