NodeMCU compile issue

Recently the Arduino IDE has stopped compiling sketches for the NodeMCU ESP8266. I have reinstalled the IDE but still get the same error message.

env: python3: No such file or directory

exit status 127
Error compiling for board NodeMCU 1.0 (ESP-12E Module).

If I type "python3" in the Terminal, Python fires up as it should, so there are no PATH problems that I am aware of.

I have been tearing my hair out for a few days, so any suggestions would be much appreciated.