I find it puzzling that in Split View using the unsorted order I can’t drag the Inbox to where I want it. Every other folder can be placed where I want it, but the inbox insists on alphabetical! This looks like a big of a bug. I’m using the latest beta.
Also, as suggested/discussed in other threads, being able to pin special folders (at least Inbox and Trash) to sort/view-independent locations would be useful.
Often it’s best to report bugs (or suspected ones) using the Support Ticket System in addition to mentioning them on the forum.