This message occurs when the scene contains meshes with animated changing topology (number of faces/vertices/polygons changes) and:
- Motion blur is enabled
- Cgeometry_Velocity render element is active
In these cases, the meshes will be rendered without deformation motion blur and they will appear black in the Cgeometry_Velocity pass (they will still render transformation motion blur though).
It is planned to at least partially remove this limitation in a future version of Corona.
Presence of mesh(es) with animated changing topology in scene with enabled motion blur and/or activated Cgeometry_Velocity render pass.
Unfortunately, currently there is no known solution to reliably compute motion blur for deformations on meshes with changing topology, unless motion vector data were computed in advance and stored within mesh vertices.
See: Motion Blur in Corona , Known bugs and limitations