Well, I just did a clean install of High Sierra and migrated my data from my boot Sierra volume after changing my keychain password to match my login password, and all was good...for about 5 minutes: my keychain was populated, and my login items launched as expected.
I then changed my keychain password so it differed from my login password, shut down, started up, and although my login items launched, my keychain was depopulated.
Keychain Access in High Sierra is pretty clearly choking on the differing login and keychain passwords, but I've got no idea what's up or, as the case may be, not up with login items.
