Hi! I tried to reproduce it for a bug report but it didn't happen in a new project, yet. But in several of my app projects I have usually 1 global GUI layer with no parallax and 1-2 normal layers for the objects.
When I use the properties to change the layer the objects often just vanish. I hit Undo then and just cut/paste the object on the right layer or rarely use right click menu to set a layer.
Does anyone else have this issue? I don't know how to reproduce it yet but it happens in multiple projects.