I think that's a known bug. R. click your account just above Inbox > Reset Folder Order. Then you can sort subfolders how you want by drag and drop.

Thank you for the helpful suggestion, but it leaves me with 2 problems:

1. When I right-click on my account just above Inbox, I get a menu that doesn't show anything identifiable as "Reset Folder Order." Snapshot attached.
2. Even if I am somehow able to Reset Folder Order manually, I don't want to have to drag and drop every time in order to return subfolders to alphabetical order.

It's unacceptable that the folders ever got out of order in the first place. It's only mildly annoying to have to click a button to restore them to alphabetical order. It's onerous to have to reorder them manually, one at a time!

Thank you again.

@AdmiralR,

I have someone else who is reporting something similar.

Please post a screen shot of your folder pane showing Inbox at the bottom / not in the top - it may help if the account line is also in the screen shot but obscured. Not asking this for proof, but so that we can see the folder icons and have the full context of what you are seeing.

Thanks

Yesterday I contacted a developer who will try get us a solution.

Wayne Mery requested: "Please post a screen shot of your folder pane showing Inbox at the bottom / not in the top"

I've posted BOTH the bottom (first) and the top (second) of the folder pane of my primary email inbox.

Thanks for investigating.