There are two methods to check which version of the plugin is currently in use.
If you open the IPR Window, the version number is displayed in the title.
You can also open the About dialog from the Arnold > Help menu and read the version number from the dialog.
Limitations
Below is a list of the current limitations and unsupported features in C4DtoA:
Most of the native Cinema 4D shaders are not supported.
The IPR requires the viewport (editor) window to be open and visible; otherwise, the IPR does not update on changes.
Cinema 4D's built-in IRR (Interactive Render Region) feature is not supported. Use the Arnold IPR window instead, which is designed to give real-time feedback on your changes.
Viewport display limitations of Arnold lights:
Arnold specific settings (like color texture, radius, etc.) are not supported.
Skydome light is not supported.
Viewport display limitations of Arnold Sky:
Physical sky is not supported.
Lighting is not supported.
If a shader network material is linked to the sky color, then only a root image shader is supported. UV settings of the image shader are not supported.
Most of the shaders in the legacy Arnold Material are not supported in the viewport.
The isometric view in the default Camera is not currently supported.
The specular flag is not supported by light linking ( exclude/include objects).
The Fur object is not supported because it's not accessible via the C4D SDK.
Native Cinema 4D Environment objects (e.g., Sky, Physical Sky, etc.) are not supported.
Motion blur with varying point count is not supported.
Projection with nested objects is not supported (e.g., using a flat projection on a Null object or a Cloner).
Some of the Texture tag attributes are currently not supported. These include Mix Textures, Seamless, Use UVW for Bump.
Arnold drivers do not work properly in a single-frame Team Render because they are executed on the client machines, writing out only a part of the image.
Changing the camera in a Stage object does not trigger an IPR update immediately. You have to move the mouse over the viewport or change the selection to trigger a proper update.
Resetting all parameters of a shader resets the title to "Arnold Shader" and the title color to grey.
Built-in spheres of a particle render have no UV coordinates. Use a Sphere child object instead.
The Arnold IPR Window does not support Team Render. This is not possible natively in C4D as Team Render is not designed for interactive rendering.
Procedurals
Procedurals have the following issues with IPR, related to the Arnold core:
No update when changing the path (e.g. moving a timeline by a .ass sequence).
No update when creating a new procedural.
Removing a shader from the procedural node renders with an invalid shader.
Procedurals do not render correctly with an object mask. The object mask overrides the shaders inside the procedural.