I'm uncertain if I can provide a project file in which this happens, because sometimes it happens and sometimes not.
A collegue of mine is working on a course, gave me a link to check for any errors, and send him the list. When he opened the storyline file to apply those changes, a lot of the things he'd done to the template and notes were gone (all the notes corresponding to the audio and all the configuration he did to the template too).
Is there a particular reason why this may happen?
By the way, we're using the latest version of Storyline 360 (V3.35.21017.0).