The subdir.mk file created automatically does not include the -I"..." files or the -D... #defines and thus dies on compiling at #include PLATFORM_HEADER. I have gotten this a few times now and attempts at rewriting the subdir.mk file are futile because it gets regenerated and making it read only also errors out. On occasion, especially after unchecking a plugin, I also tend to get extra files that need to be excluded from the build OR files that need to be included that for some reason got excluded. This is really frustrating. Restarting Simplicity Studio and pressing Generate again does not seem to fix either.