I took screenshots but I'm not sure how to add them ^^ I have to go through an external site, right?
I understood why I have this problem but I don't know how to solve it on my second Prefab.
I noticed that on my first working Prefab, at the top right, just below “Alpha 21.1 (b16)”, it says the name of the Prefab.
On my other two Prefabs, this is not indicated. After several tests, I understood that the name of the Prefab must be written for me to be considered on it. If I move away a little, on my first Prefab which works, I get the error.
So I managed to destroy my switch by landing on the block of my third Prefab.
However, on my second Prefab, even when deactivating the flight, the name of my Prefab is never written at the top right of the screen.
I changed the name of the Prefab but it still does not appear.
Edit: I don't know if there is a better solution but I reselected my structure and copy/pasted it onto a new Prefab. When saving and reloading the Prefab, the name appears and the switches work.