The PythonErr.log reports the python error messages. PythonErr2.log contains the traces written in the code.
You will need to put some traces in it to make sure it is going down the correct part of the if test. Or I can, although that is one wonder I never see.
Where do I find PythonErr.log? I tried searching my computer and couldn't find it. I found PythonErr2.log in the My Games folder.
How do I add a trace? I think I'm supposed to use CyInterface.addMessage to get it to output a string to the message log, correct?
I can attach another save game where a city will build the Field as soon as you end the current turn, if that would help.