I've got a simple console project where I'm reading two Excel-files. The Excel-files are included in the project ("add existing item") and I've marked them with "Copy to Output Directory". However, they are not copied to the debug-directory when debugging/running the code.
I feel like I've forgotten something trivial. What do I need to do more?
Silly question but are you running in debug mode? I've made the same mistake and realised I was in release mode.
Changes to non-source code files don't cause a rebuild to occur - they aren't considered when the compiler does it's out of date checking.
Try forcing a complete rebuild by deleting your output directory completely (sometimes doing this from within Visual Studio isn't complete).
It may be that the files haven't been copied across because a full build hasn't been run.