Oh, hang on, I think I just spotted something in your video:
When you touched the little menu icon when viewing it one of the options was "format as portable". So have you formatted it as internal storage? That could explain why it's not visible as a separate device to the file explorer, and possibly why the external storage path was pointing back to the emulated card.
Every word I've written in this thread has been on the assumption that the SD card was being used as removable storage, so if it's formatted as internal ("adopted") that's very different. Unfortunately it's also something I've never done, so have no way of investigating the behaviour of that.