Impress removes connectors during save on pptx documents


I need to work on a PowerPoint - File and also save it as power point. I need a chart in there which uses connector arrows. Unfortunately upon save and reopen all the errors are moved to the top left corner of the slide. Is this a known bug? Can I do anything against ist?

My LibreOffice Version is: Build-ID: 1:6.3.4-0ubuntu0.18.04.1~lo2


Same problem here, with Build ID 6.4.5-2 on Arch Linux. Connectors disappear when saving as pptx.