This is related to Creative device marked as unsaved every time even though nothing changed. and Removing @editable locks the value of a constant
But it not being saved is not necessarely a bug, it is to avoid data loss (if you save something it will discard all previous data), this happens when you make changes in your code that modifies the structure of the classes in a breaking way (even non-exposed properties)… It can happen with scene graph entities, components or creative devices exposed to editor.
To fix it, you need to explicitly tell the modified property that you want to discard the old values (if is not needed anymore), or do a “diff check” to choose which of the confliciting changes to keep on that property. Things affected by this will have a exclamation mark warning on the side. You can read more about loose properties on Data Recovery Tool in Unreal Editor for Fortnite | Fortnite Documentation | Epic Developer Community (Tool Currently only available to Scene Graph, not available on Creative Devices)