Error after saving file PPTX file

[Rita-Bubnova]

          Dear @ShockwaveNN , we have experienced the same problem multiple times with different Powerpoint presentations.

I've attached a minimal example that opens fine in Powerpoint, opens fine in ONLYOFFICE when uploaded to Nextcloud, but is defect when downloaded again via "File > Download As > PPTX". It still works fine if downloaded directly from Nextcloud.

This is with Docker image docker.io/onlyoffice/documentserver:latest, Nextcloud 29.0.7 and the ONLYOFFICE Nextcloud App version 9.4.0 (but I suspect this could also be triggered without Nextcoud at all).

Reduced-6.pptx

Defect file downloaded from ONLYOFFICE:
Reduced-6-dl.pptx

My initial assessment as a layperson: The slide contains an animation referencing (as far as I can tell) an object that isn't there anymore. So it is somewhat gone bad, but this was not "crafted" this way, users somehow end up in this situation by normal Powerpoint use and, more importantly, the file still works fine in Powerpoint.

Originally posted by @adsche in #1185 (comment)

[ElenaMaaya]

@adsche, thank you for report!
I can confirm that the problem exists. I created ticket 70735 in our issue tracker.