ViewCullPlugin hides objects on setViewpoint

[Amoki]

Describe the bug When setting viewpoints with ViewCullPlugin enabled, some objects are hidden. Moving the model out of sight and bring it back restores the objects.

To Reproduce Steps to reproduce the behavior:

1. bcfViewpointsPlugin.setViewpoint(viewpoint) (the model must go in background during viewer.cameraFlight.flyTo
2. See missing objects.
3. Move the model out of sight then back in
4. Objects are now visible

Expected behavior ViewCullPlugin shouldn't hide objects on flyTo

Screenshots

Additional context There may be another underlying bug: The first time I call setViewpoint, the model goes completely out of sight. The next time I call it (after manually resetting the camera), the model moves but doesn't totally go away for a few frames.