@maxgerhardt yes I am also on an Apple machine. I have installed the arm tool chain and can run it from the terminal/CL but I can’t seem to get platform IO to recognize its already installed and just to use it.
The marlin branch I am using is here
the Platformio.ini file is also there, The only change I am making is changing line 21 from
default_envs = megaatmega2560
to
default_envs = LPC1768
to make it compile for the board I am using