In addition to enabling the commands, I think you need two things:
- r.ForceDebugViewModes=1 (DefaultEngine.ini). Otherwise FSceneView::ConfigureBufferVisualizationSettings() is not being called.
- After setting that variable, you need to recook your content, which will now include Engine/Content/BufferVisualization/*.uasset. Otherwise FBufferVisualizationData::Initialize() won’t find the visualization materials.