Apple Mail IMAP Path Prefix not working
Last week I upgraded my iMac from Snow Leopard to El Capitan. At first, the mailboxes on the iMac didn't look the same as they did on my MacBook (running Sierra). Once I discovered the advanced setting of IMAP Path Prefix and entered "INBOX" into that field, the mailboxes on the iMac straightened out.
Yesterday I upgraded the iMac to Sierra, and something went wrong. Even though the IMAP Path Prefix setting still says "INBOX," the prefix is not showing up in the Mailbox Behaviors settings window, and the mailboxes in Mail itself are back to being a jumbled mess. Apparently, the "INBOX" setting isn't being recognized properly.
Here are screenshots of the Mailbox Behaviors windows from my MacBook (left) and iMac (right); note the absence of the "INBOX" prefix on the iMac:
If I log out of my normal account and log in to the iMac through a test user account, the "INBOX" prefix works fine. So apparently something is corrupted in my account's settings for Mail. Can anyone suggest how I might fix this problem? Thank you!
iMac (27-inch Mid 2011), Mac OS X (10.6.8)