#define FASTLED_ALLOW_INTERRUPTS 0 //Tried with and without this. same results.
#include "FastLED.h"

// How many leds in your strip?
#define NUM_LEDS 15

// For led chips like Neopixels, which have a data line, ground, and power, you just
// need to define DATA_PIN.  For led chipsets that are SPI based (four wires - data, clock,
// ground, and power), like the LPD8806 define both DATA_PIN and CLOCK_PIN
#define DATA_PIN 16

// Define the array of leds
CRGB leds[NUM_LEDS];

void setup() {
    Serial.begin(115200);
    Serial.println("Hello, you've entered setup()...");
    FastLED.addLeds<WS2811, DATA_PIN, RGB>(leds, NUM_LEDS);
}

void loop() {
  // Turn the LED on, then pause
  leds[1] = CRGB::Red;
  FastLED.show();
  Serial.println("red...");
  delay(1000);
  Serial.println("blue...");
  // Now turn the LED off, then pause
  leds[1] = CRGB::Blue;
  FastLED.show();
  delay(1000);
}