ID 500539 - Unable to promote Locator List attributes

Problem summary
Unable to promote Locator List attributes

Customer reported version
Mari 4.8v1

Customer reported platform
Multiple

Steps to reproduce

1) Open any project

2) Create a Projection node

3) Group the Projection node

4) Dive inside the Group and open the Projection node properties

5) Inspect the Locator List property

Expected behaviour
The Locator List property should have a 'wrench' button that can be clicked to expose it in the Group node's properties.

Actual behaviour
The promote button is not present.

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Mari 5.0v1 - Windows 10 - CentOS 7.9
Mari 4.8v1 - Windows 10
Mari 4.7v3 - Windows 10 - CentOS 7.9 - regression

Unable to reproduce bug in:
Mari 4.7v2 - Windows 10 - CentOS 7.9

Earliest version tested
Mari 4.7v2 - This issue doesn't appear in this version and has regressed