I looked into this some more, and it seems to be an issue due to ShooterGame so heavily relying on the semi-legacy Classes folder to the point that it didn’t even have header guards or properly set-up include paths. This essentially made it incompatible out-of-the–box with the in-editor class wizard.
We’ve updated this sample (as well as some of our others that were also set-up in this way) for 4.8 to reflect current practices in header layout, and this should address the issues with the in-editor class wizard.