PPS attachment 139226 [details] has no sound in slideshow.
Tested both in Lin and Win with LO 7.1+. Inherited from OO.
Note: if I right-click Save media in MSO, it says "This linked item can't be saved because it's stored outside presentation. Only embedded items can be saved".
But it plays sounds in MSO both in right-click Preview and in slideshow and WAV is seen in file if saved as PPTX.
Created attachment 166110 [details]
Sample resaved in MSO as PPSX
If sample PPS is resaved in MSO as PPSX, sound plays.
Created attachment 166111 [details]
Sample resaved in MSO as PPT
Also *no* sound if sample resaved in MSO as PPT.
Version: 188.8.131.52.alpha0+ / LibreOffice Community
Build ID: 67e47070a7580a17804adce812cc2f98bfe7b51f
CPU threads: 16; OS: Linux 5.13; UI render: default; VCL: x11
Locale: fi-FI (fi_FI.UTF-8); UI: en-US