[This is the most recent and most relevant post on this topic so I'm posting here.]
There is an important part of this that no-one here mentioned. After you copy your component(s) and want to paste it into another app or part of the same app, you must select a relevant component to paste it into, like a screen or an arrangement. If you attempt to paste into a button or an image, you will corrupt your app.
Also, don't paste objects into Table Arrangements, same problem as above.