In several user guides, we advise users to give their graphics useful names rather than sticking with the default Graphic1, etc. Yet we don't follow this advice ourselves!
If graphics were given easily recognisable names (for example numbered graphics being called Fig1, Fig2, etc., and inline graphics things like FooIcon), then it would be much easier to handle the "disappearing graphics" problem. The initial .odt file could be copied and unzipped, and if any graphics were not shown in Writer, they could be retrieved from the graphics subdirectory and displayed alongside with a simple display program like xv, feh or eog. This would make editing/proofing much easier.
Even if the file was actually stripped of graphics on saving (as shown by a drastic reduction in its size), the graphics themselves would be safe and could be zipped and uploaded along with the text file.