While helping the Chrome guys debug a change they made to some keyboard shortcuts in their development tools, we've found that the reason why a new shortcut wasn't being captured by Chrome was due to 1PasswordAgent being running on the background.
It doesn't matter if the browser is running the 1Password extension or not. As long as the agent is running, the shortcut is captured and Chrome never gets a hold of it.
This is currently only an issue on Chrome Canary where the shortcut has landed, but it would also be an issue for any webapp which uses the same keyboard shortcut.
Changing the shortcut on 1Password is the easiest solution for now, and for me personally it's not a big issue as I never used that shortcut for 1Password anyway, but I feel like this is an issue with 1Password Agent that should probably get some attention, so I thought I'd let you guys know.