In the latest beta version I've noticed that the ctrl+\ is enabled everywhere in Windows. Having any app running in the foreground and hitting ctrl+\ will open 1pw mini.
Ctrl+alt+\ is supposed to be the shortcut you should use if you are outside of your browser (or in your browser to show all items).
1Password Version: 6.5.396
Extension Version: Not Provided
OS Version: Windows 10
Sync Type: Not Provided