Create some slide. Make sure master has page numbers and add page / slide number to the slide. Save in OpenOffice-Format and in Microsoft Powerpoint PPTX format. Close file and reopen PPTX file. Slide numbers are gone, they've likely never been saved in PPTX in the first place, as MS Powerpoint-Viewer (https://www.microsoft.com/en-us/download/details.aspx?id=13) doesn't show them either. This happens on several testet LibreOffice variants (e.g. 4.1.6.2 Linux, 5.4.6.2 Windows) up to and including 6.0.3.2 (x64) Windows and Linux.
Created attachment 141767 [details] Simple Slide in OO-Format with number (and footer text)
Created attachment 141768 [details] Simple Slide (same as attachment #1) saved as PPTX
It seems noteworthy that there is a field with type "slidenum" in ppt/slideMasters/slideMaster1.xml but no (corresponding) entry in ppt/slide1.xml. The "solution" in https://stackoverflow.com/questions/36190387/how-can-i-add-slide-numbers-to-a-powerpoint-presentation-using-open-xml-net-sdk indicates there ought to be such a field. Indeed, adding <p:sp> <p:nvSpPr> <p:cNvPr id="127" name="CustomShape 4"/> <p:cNvSpPr/> <p:nvPr> <p:ph type="sldNum"/> </p:nvPr> </p:nvSpPr> <p:spPr> <a:xfrm> <a:off x="8741520" y="6247440"/> <a:ext cx="2840400" cy="472680"/> </a:xfrm> <a:prstGeom prst="rect"> <a:avLst/> </a:prstGeom> </p:spPr> <p:txBody> <a:bodyPr lIns="0" rIns="0" tIns="0" bIns="0"/> <a:p> <a:pPr algn="r"/> <a:fld id="{BE8C60C3-C7BB-4A63-A38B-623C61B19D0D}" type="slidenum"> <a:rPr b="0" lang="en-US" sz="1400" spc="-1" strike="noStrike"> <a:solidFill> <a:srgbClr val="006699"/> </a:solidFill> <a:latin typeface="Arial"/> <a:ea typeface="Arial"/> </a:rPr> <a:t><number></a:t> </a:fld> <a:endParaRPr b="0" lang="en-US" sz="1400" spc="-1" strike="noStrike"> <a:solidFill> <a:srgbClr val="006699"/> </a:solidFill> <a:latin typeface="Arial"/> <a:ea typeface="Arial"/> </a:endParaRPr> </a:p> </p:txBody> </p:sp> just before </p:spTree> seems to create a slide number which does not vanish on saving / reopening.
Well, obviously there seems more to it, as not only slide number but also footer and maybe other fields get lost upon saving as PPTX and reopening. For me footer and page / slide number are quite important e.g. for collaboration or printouts and thus would be very good to have.
*** This bug has been marked as a duplicate of bug 111860 ***
*** This bug has been marked as a duplicate of bug 59323 ***