There is more than one way to import an image.
If you drag n drop directly from the Finder to a scene, the cursor will be the centre of the dropped image.
This is the same if you use the Add file menu in the resources then you will also have to drag n drop.
If you Copy n Paste or use the Import Menu, the image should centre.
I just tested an Import using the Menu to import.
492x912 image into the same dimensions scene. Imported exactly edge to edge. Then enlarged the scene 100px w,h each.
The image still imported centred.