Hiya,
hmmm, Nano 33 IoT definitely works ok, I've just checked and everything compiles fine.
ESP8266 should not be mentioned anywhere, the config file generated by the Code Builder should take care of that. Are you using a fresh template generated by the Code Builder?
Actually, if you are using Arduino IDE then it could be another thing, Arduino IDE can be a dumb ass as it relies on you correctly specifying the serial port and telling it
exactly which type of device is connected to it.
If you had an ESP8266 plugged in before and left the serial specifying an esp8266 than Arduino IDE will look in the ChipChop code for the esp8266 wifi library instead of the Nano
If it's not the Arduino IDE issue, could you email me your code so I can try and compile it and see if I can reproduce the problem.
G