Created attachment 199208 [details] Original PPS slideshow The first attached file is a PPS, which is the first attachment of this KDE bug report: https://bugs.kde.org/show_bug.cgi?id=276667 Direct link to the same file: https://bugs.kde.org/attachment.cgi?id=61401 - Open attached PPS file, - Since it's a PPS, it's going to start a slideshow, switch to edit mode by right-clicking it and choosing Edit Presentation, - Save as PPTX, - Close LO, and try opening PPTX in PowerPoint. => PowerPoint fails to open the file, and attempts to repair it. The same happens if you convert PPS to PPT in PowerPoint first (second attachment), and attempt to convert that to PPTX in Impress. Oberved using LO 25.8.0.0.alpha0+ (60b64338c2a1236cdc98f3834cc77fc3006fc241) / Windows. To rule out bug 165036's involvement, also checked and observed in preceding 25.2.0.1.0+ (eb83239ef26a8ddf77d82d1f6805c58ee366c172), and a few older versions: 6.0.0.3, 4.4.0.3, 3.3.0. Interestingly, when converting using --convert-to, the result does open in PowerPoint. It's not perfect, but that's for a different bug report.
Created attachment 199209 [details] PPS converted to PPT in PowerPoint
Created attachment 199231 [details] PPT with breaking slide (5th) It's slide 5 that's the problem. There's some kind of animation that gets written with the slide in the buggy case (under a <timing> tag) that breaks the file.
Created attachment 199232 [details] PPTX of slide 5 (made in PP) This is the same slide saved as PPTX in PowerPoint. Impress already imports it with no animations. The animations are imported from the PPT.