ID 509282 - Color swatches in the shelf show as grey until a project is closed or loaded

Problem summary
Color swatches in the Shelf show as grey until a project is closed or loaded

All swatches are shown as grey again if Mari is relaunched.

Customer reported version
Mari 5.0v4

Customer reported platform
Multiple

Steps to reproduce
1) Open any project in Mari

2) Open the Shelf palette and create a new shelf

3) Drag a color swatch (not grey) from the color picker to the Shelf

4) You will see it shown as grey

5) Close your project, and open the Shelf palette, you will see the color swatch now shows correctly in the Shelf

6) Relaunch Mari and the swatch will be shown as grey again

Expected behaviour
The color swatch should have the correct color.

Actual behaviour
The color swatch shows as grey in the Shelf until you close or restart a project, and then it shows correctly until a new Mari session is launched.

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Mari 5.0v4 - Windows 10 - CentOS 7.9
Mari 4.8v4 - Windows 10
Mari 4.8v2 - Windows 10 - CentOS 7.9 - regression

Unable to reproduce bug in:
Mari 4.8v1 - Windows 10 - CentOS 7.9

Earliest version tested
Mari 4.8v1 - This issue doesn't appear in this version and has regressed