Sorry to hear, that your problem is more complicated than i've expected ...

So you're saving your own scenes to hard-disk and still after that a rendered image of this scene won't save ? But loading other prebuilt scenes will allow you to save the rendered image ?

A weird sounding problem, definitely ... sorry, no idea from my side right now ...

Maybe it would be helpful to e-on programmers, if you could include a video recorded with a desktop-cam program (those ones being used for tutorial-movies), go step by step through the process of saving a rendered image from a pre-built scene and do the same with your own scene and render, not being able to save the image.
Maybe that way, they could get an idea, even if they can't reproduce it themself, but could visually watch the error happen on your system and Vue version ... ?!