Hi Daniel
Firstly the MEX files are created using MCUXpresso Config Tools version 12.0.
A project is then created in MCUXpresso IDE version 11.6.0, with the MEX file dropped into this.
I have attached the MEX file to this message - it does not contain commercially sensitive information.
Within the MCUXpresso IDE, in I get:

During compilation, also within MCUXpresso IDE, I get:

Also, the IDE keeps changing the runtime library to RedLib from NewLib, which also breaks the build as RedLib does not support complex numbers which we require.
Is there a recommended workflow to avoid such problems, or a tweak to a .cproject or .mex file, etc?
Kind regards
Gary Partis