ID 408344 - When you import an object into a scene sometimes the materials aren't being rendered correctly

Problem summary

This mainly occurs when changes are made to the materials in the Shader Tree.

Customer reported version
modo.13.1v1

Customer reported platform
10.14

Steps to reproduce

1) Press the F6 key to open the Presets browser.

2) Select Cloud Assets>Meshes>Vehicles>Spacecraft and import the AlphaOmega by Funk model.

3) Once this is imported press the F8 key to open the Preview Render window.

4) Makes changes to the imported materials in the Shader Tree, such as deleting materials and then undoing this action.

5) You will notice that the materials are no longer being rendered correctly, like the gif below: 

If not repeat step 4 until this behaviour occurs.

Expected behaviour
All of the materials should be rendered.

Actual behaviour
None of the materials are being rendered.

Workaround
Unknown. 

Reproduced by support

This bug has been reproduced in:
13.1v1 - Windows 10 - MacOS 10.14 - Centos 7 -regression

Unable to reproduce bug in:
13.0v1 - Windows 10 - MacOS 10.14 - Centos 7

Earliest version tested

13.0v1 - This issue doesn't appear in this version and has regressed.