Answer
Check for a solutionset.yaml file inside the FNDBAS folder of your workspace — a newly created component has to be explicitly added to that solutionset.yaml to actually show up in the tool navigator. After adding the new component's entry there, use the 'Reinitialize the SolutionSet' option from the RMB (right-click) tool menu to make Developer Studio pick up the change, rather than expecting it to appear automatically just because the files exist on disk.