edited bitmaps not saved

I have in my document a rounded rectangular shape of which I want to change the background to a portrait picture of a person via the ‘area’ menu. No problem. I changed it without a problem. But afterwards, I wanted to change the picture to the same picture but with a bit more padding to it, so I edited the picture in GIMP after which, in the area menu, I deleted the previously added picture and uploaded the new version. But upon saving the writer document and reopening, the first version of the picture reappeared.
Any idea what might cause this inability to save? I would guess it’s a cache-related thing, but how do I change it?

Don’t post twice! This is a duplicate of 262630/edited-bitmaps-not-saved/. Go there and delete it. I closed it to prevent answers there.