ID 407494 - Groups containing instance items and source meshes are rendering incorrectly.

Problem summary

When you render a group which has a source mesh and instance items inside, all instance items are rendered regardless of if they're in the group or not.

Customer reported version
13.1v1

Customer reported platform
Windows 10

Steps to reproduce

1) Download and open the attached scene.

2) Open the Groups tab and notice that they're two different groups, one with 2 instances and another with the same 2 instances and the source item.

3) Now go to the Shader Tree and in the source+instances materials Properties set the Item to instances only.

4) Press the F9 key and notice that 2 items are rendered as they're only 2 items in the group, this is correct behaviour.

5) Now set the Item to source+instances and press the F9 key, notice that 5 items are rendered, when the group only contains 3 items. All instances are being rendered regardless if they're in the group or not.

Expected behaviour
Only 3 items should be rendered, the source item and two of the instances.

Actual behaviour
All of the instances are being rendered regardless of whether they're in the group or not.

Workaround
Unknown. 

Reproduced by support

This bug has been reproduced in:
13.1v1 - Windows 10 - MacOS 10.13 - Centos 7

13.0v1 - Windows 10

12.2v2 - Windows 10

12.1v2 - Windows 10

12.0v1 - Windows 10

11.2v3 - Windows 10

11.1v1 - Windows 10

11.0v3 - Windows 10

10.2v4 - Windows 10 - MacOS 10.13 - Centos 7

Earliest version tested

10.2v4 - This issue appears to be in all versions of the product.