Thanks Anlv
It looks like its adding the emitter into a null is what's causing it.

Fixed with deferred CallCommand(1062577) (no sub-id (1067510) silently no-ops). Emitter fields greys if the emitter/group are parented under the setup null or generator. Sibling placement below plugin object + rename works fine.

I'm trying to create a Mesh Emitter with the selected object as Geometry, same as Simulate > Mesh Emitter when geo is already selected.

Script Manager (works):

import c4d
doc = c4d.documents.GetActiveDocument()
geo = doc.GetActiveObject()
doc.SetActiveObject(geo, c4d.SELECTION_NEW)
c4d.CallCommand(1062577, 1067510)  # Mesh Emitter
c4d.EventAdd()

From an ObjectData plugin (doesn't): Create button builds a polygon object (100 pts). I don't call CallCommand from MSG_DESCRIPTION_COMMAND; the handler queues work and calls SpecialEventAdd, and a MessageData plugin runs the Mesh Emitter command in CoreMessage. Also tried having MessageData invoke a CommandData that runs the same CallCommand.

Same result either way: active stays on the grid, no new emitter in the scene.

So it's not selection or empty mesh. The command does nothing from plugin code but works in Script Manager.

Does CallCommand(1062577, 1067510) only work in certain contexts? What's the supported way to create a Mesh Emitter from a description button without BaseObject(Ofpmeshemitter) + manual SetLink (Geometry grey out in the AM)?

Ofpmeshemitter = 1062577. Script Log records CallCommand(1062577, 1067510) when using the menu.

Thanks Ferdinand. I actually made a powershell script that did essentially the same thing as #2. Deletes the current version in the c4d plugins folder, copies the newest Build and copies in the res folder.

Is there any way to set Visual Studio to copy the whole res folder to the /bin/release/plugins/xxx folder instead of using a shortcut? When copying the plugin to the cinema plugin folder the res folder is empty...you have to go back to the res folder (which seems to be a shortcut to itself?) and manually copy the contents into the res folder in the cinema plugin folder.

Both Cinema_4D_CPP_SDK_2025_0_0 and Cinema_4D_CPP_SDK_2025_0_1 do not have the same file structure as Cinema_4D_CPP_SDK_2025_3_1, no CMakeLists.txt, ect

Is this correct? Redownloaded/expanded both just to confirm.