I can confirm this too, using LibreOffice 3.3.0 under Ubuntu 10.10.
But there's a way to partially solve this:
1 - Make the presentation
2 - Save as PPT;
3 - Close Impress;
4 - Open the PPT presentation;
5 - Save as ODP;
6 - Open the ODP presentation.
It works to me. And I suppose that process must be repeated each time when you change or add a new background.
I can confirm this too, using LibreOffice 3.3.0 under Ubuntu 10.10.
But there's a way to partially solve this:
1 - Make the presentation
2 - Save as PPT;
3 - Close Impress;
4 - Open the PPT presentation;
5 - Save as ODP;
6 - Open the ODP presentation.
It works to me. And I suppose that process must be repeated each time when you change or add a new background.