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"Make Single User -> Object" does not do anything to objects linked to multiple scenes
Closed, InvalidPublicBUG

Description

System Information
Operating system: Windows-2012ServerR2-6.3.9600-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 416.81

Blender Version
Broken: version: 2.83.0, branch: master, commit date: 2020-06-03 14:38, hash: rB211b6c29f771
Worked: last observed working on 2.7x/2.77. Bug is present in 2.82.

Short description of error
"Make Single User" operation does not make the selected objects single user, as long as only "Object" is selected. The operation performs correctly when "Object & Data" is selected, but in that case it makes the mesh itself single user as well.

Expected behavior: "Make Single User -> Object" breaks the link between objects in different scenes. "Make Single User -> Object & Data" breaks the link between objects and gives each it's own mesh.
Observed behavior: "Make Single User -> Object" has no effect other than renaming the object. "Make Single User -> Object & Data" breaks the link between objects and gives each it's own mesh.

Exact steps for others to reproduce the error

  1. Start with the default startup file
  2. Scene list (top right) -> "Linked Copy"
  3. Select object (in the "Scene.001" newly created scene or in the original scene)
  4. "Object" -> "Relations" -> "Make Single User" -> "Object" <--- the error happens here
  5. Observe that the objects name changed as if a new unique instance of the object was created
  6. Rescale the object
  7. Switch to the other scene (e.g. "Scene") and observe that the original object also changed name and scale <--- the error presents itself here

Work around
Here is the sequence of actions that works around this bug:

  1. Start with the default startup file
  2. Scene list (top right) -> "Linked Copy"
  3. Select object (in the "Scene.001" newly created scene or in the original scene)
  4. "Object" -> "Relations" -> "Make Single User" -> "Object & Data"
  5. Select the object in the scene and pick the original mesh for it rather than the newly created one
  6. Rescale the object
  7. Switch to the other scene (e.g. "Scene"), there is no change in scale and the two objects are fully unlinked

Event Timeline

Additionally, the following steps continue to make the problem worse:

1-8. Follow the steps to reproduce the error

  1. Shift+D - duplicate the object ("Cube1.001") <--- a second error happens here
  2. Observe "Cube1.002" object being created in "Scene"
  3. Switch to "Scene.001"
  4. Observe "Cube1.002" being created in "Scene.001" as well <--- the second error presents itself here, the cube should have only been created in one scene, not both scenes.

I'm not sure what happens here, but possibly when scene is linked-copied, the collections are linked instead of being duplicated. It seems like duplicating collections would be the correct action here rather than linking *all* contents of a scene. It's not super clear how to unlink the collections from the second scene/make them single user.

*A counterpoint to this theory is the following steps to reproduce the error:
1-2. Follow the steps to reproduce the error
2A. Select "Collection" (in "Scene.001", the newly created scene)
2B. Right click on "Collection" in the outliner, "ID Data" -> "Make Single User"
3-7. Continue steps as in the original bug report.

The expected result would be fixing the original issue, but the original issue remains even after explicitly trying to make the collection single user (making it single user does not seem to have any visible effect).

Germano Cavalcante (mano-wii) renamed this task from "Make Single User -> Object" does not do anything to objects linked to several scenes to "Make Single User -> Object" does not do anything to objects linked to multiple scenes.Fri, Jun 26, 4:10 PM
Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Confirmed.
Germano Cavalcante (mano-wii) changed the subtype of this task from "Report" to "Bug".
Bastien Montagne (mont29) claimed this task.

There is no bug here, not only the objects are shared between two scenes during linked copy, but also there collections. So technically there is only one Object user (the collection shared between scenes).