SES 2.20 seems to have some trouble handling these files. C/C++ files are fine. What I see is that regardless of how the "Exclude From Build" property is set the right-click option is always checked. In some cases I cannot exclude a library no matter what and must remove it and add it to the project.

In my case I have a Library folder within the project and I have included several different builds of EMBOS (debug, trace, profiling etc) and I'd like to include different libraries.