ID 404999 - Image Manager looses images loaded from a Shelf

Problem summary
Image Manager looses images loaded from a shelf when the project is reopened 

Customer reported version

4.5v2

Customer reported platform
windows10

Steps to reproduce

1) Open Mari and an example project

2) Open the Image Manager and load 2 images 

3) Create a new Shelf and drag and drop the images from the Image Manager onto the new Shelf

4) Delete the images from the Image Manager and re-load them from the shelf by clicking on each of them

5) Save>Close>Reopen the project

result: The images are no longer in the Image Manager. If the images are loaded in nodes/layers, the user has to manually re-import them as the node will show the red X image. 

Expected behaviour
Images should be saved in the project regardless of the way they have been imported

Actual behaviour
Images imported to the Image Manager through a Shelf are lost after re-loading the project 

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:

4.5v2 - Windows 10 - CentOS 7

3.3v1 - Windows 10 

3.0v1 - Windows 10 

2.6v5 - WIndows 10 - CentOS 7 - OSX 10.12.6

Earliest version tested

2.6v5 - This issue appears to be in all versions of the product