J-M-L:
The WS2812B use interrupts heavily but you don’t see it
Same goes for the SDI was suggesting pretending you have APA102 connected - sure the LED would not do anything (disconnect them) but the code would handle them. If that works that would be an indication for the challenge you have
Well from what you said, I commented out this line:
FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NO_OF_LEDS).setCorrection( TypicalLEDStrip );
And replaced it with this instead:
FastLED.addLeds<APA102,11,13,GRB>(leds, NO_OF_LEDS).setCorrection(TypicalLEDStrip);
But the same thing happens again. The LED strip effect doesnt work.