I’m using Libre Office v220.127.116.11 (x64) on Windows 10. I want to present an Impress Slide Show using a presentation mouse, which works by transmitting PageDown and PageUp. Both these buttons on the presentation mouse produce the same behaviour in Impress Slide Shows - they advance the presentation by one slide. I also tried using my keyboard, and PageUp, PageDown, Ctrl+PageUp, Ctrl+PageDown, Left Arrow and Right Arrow all advance the presentation by one slide.
According to this help page
which details keyboard shortcuts for Impress, if there are no effects, then PageUp should display the previous slide. Also, Ctrl+PageUp should display the previous slide, irrespective of any effects.
How do I show the previous slide in Impress using the keyboard or, ideally, a presentation mouse? And/or is this a bug?