When you are switching to another layout, all objects from the current layout are destroyed. If the same objects exist on the new layout, their instances will be re-created, possibly with different UIDs.
You can set an object as Global, it will be transferred to other layouts. But you should be careful, it's very easy to mess things up with global objects. For example, if you switch to "eren" layout and then back to "main", you may end up with two instances of Eren object. In this game I wouldn't recommend it.