In the hierarchy, I have two meshes called "Cube" that I'd like to merge together:
Most answers that I've found online say to Shift select both and press Ctrl+J to merge them. However, weirdly that doesn't work in my case. If I select both the green triangles with dots and press Ctrl+J, nothing happens. If I select both of the yellow triangles and press Ctrl+J, nothing happens. If I select all four of these and press Ctrl+J, nothing happens. In all of these situations it's as if I wasn't pressing J at all, nothing changes on screen.
Is there something weird about my situation that would cause Ctrl+J to not work?
It's especially frustrating that Blender 2.8 doesn't give any errors or any reason why it's not joining the meshes as I wish it to.