For me the this bug seems solved. I'm don't know what do you change between versions, may be the coin library.
I tested again with the same machine, graphics driver using.
The image hide/show visibility is working. I'm also saved the file successfully.
There's is Remanent another bug with the transparency of the image (png in my case)
I’m just struggling with the transparency that when the grid is not shown is is rendered black. But when grid is present is shows normal.
OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16110 (Git)
Build type: Release
Branch: (HEAD detached at upstream/releases/FreeCAD-0-18)
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0