Please email supportdos2@larian.com, with a description (or link to this topic) and a save where this has happened, or (even better) can be reproduced (or a Dropbox or Google drive link, etc).
I couldn't reproduce this in a quick check in a new game, though only had 2 characters... Do stairs count as uneven ground?
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin 2\PlayerProfiles\<ProfileName>\Savegames' folder. In Windows Explorer you can zip file(s) and folder(s) by right clicking on it/them and selecting 'Send To | Compressed (zipper) Folder'.
