Update: Thank you for your response. Just to clarify, the issue happened on my iPhone only. I wasn’t using cloud saving or any other devices.However, it seems the problem might not be about losing data, but rather that saving is not working at all. For example, when I choose "Save & Exit" in the Map Editor and then go to CUSTOM CONTENT > CREATE > MAP, it shows “There's nothing here!”. This makes me think the save function itself might not be working.
Thank you for the update! We've identified a fix and an update is currently being checked by QA - we hope to deliver the fix soon!