From the last 2 photos it definitely looks to me as though it’s not inside the RG (hence why I asked if you were sure)…
But if you’re sure it is (and the element tree confirms it) then there’s obviously something else wrong here, so you’ll need to share some more details (although it still looks to me as though the RE is not inside the RG)…
(in fact, from your screenshots, it looks to me as though the RE is inside a parent Group, which is itself not inside the RG)…
Feel free to share a pic of your element tree if you’re not sure yourself where things are…
Where is it? How I put it in the RG? I’ve just clicked the card in the reusable elements list and placed it in the repeating group as it is shown in the tutorial video…
I think it’s acting weird because your reusable might be bigger or the same size as the repeating group.
In your picture of the Elements tree just drag the post_card on top of the RepeatingGroupPosts. After that there should be a + to the left of the repeating group indicating that there is something inside of it. Then you still need to set the Data source of the reusable element to Current cell’s Post