I think I mislead you in my initial posts with the different project names. From testing in my computer I believe the problem is still related to filenames. By adding the same project file, with just a different filename, the error appears (when the filename doesn't match the project name). (Note that I'm not trying to add both projects with the same name to the workspace, one after the other; each time, I went and cleaned the .workspace from all references to the project before adding the other one).
Hopefully the files I post in the attachment will help clarify.
I've attached workspaces and projects that I think illustrate the problem. Within you'll find the following:
CodeLiteWorkspace_INITIAL.workspace: workspace before adding any project
CodeLiteWorkspace_AFTER_ADDING_JUST_UTILS_PROJECT.workspace: the initial workspace after adding the project which loads correctly (this is already the converted project).
CodeLiteWorkspace_AFTER_ADDING_JUST_UTILS_CONVERSION_PROJECT.workspace: the same but after adding the (problematic) project, which throws the "AddToBuildMatrix" error.
Utils.project: project file that loads succesfully.
Utils_Conversion.project: project file that throws the error when added to the workspace. Same file as Utils.project, but renamed.
Again, thanks for the help, and for the tips on the plugins (which I would eventually come up against
)