I just installed micropython:
MicroPython v1.8.7-7-gb5a1a20a3 on 2017-01-09; ESP module with ESP8266
onto my NodeMCU.

I tried the example code for APA102 driver at: https://docs.micropython.org/en/latest/esp8266/esp8266/quickref.html#apa102-driver

whenever I call the write()-method, the LED that comes after the nth led configured with
apa = APA102(clock, data, n) will light up white.

for example:

apa = APA102(clock, data, 2)
apa[0] = (255, 0, 0, 31)
apa.write()

will result in a red first LED and a white third LED. The second LED stays off.

Any Ideas what could happen here?

Thanks in advance