The auto log out feature is not functioning properly. I've got it set to log out after 20 minutes of inactivity and it doesn't. It just stays logged into my lastpass, even overnight. I'm using Chrome and I've noticed this issue on a couple different computers.
Obviously this is a major security issue as my computer is completely open and all my passwords are available to anyone who comes across my computer.
This is not a bug, but I'd say a super bug and should be immediately fixed by LastPass.
Make sure that your computer isn't going to sleep before the set inactivity timeout. Browsers still running in the background can also cause problems.
Also, consider the information at risk by leaving the workstation unlocked while unattended. It would be wise to lock the OS with a password when you're away from the keyboard.
Could you also check this setting in your LastPass extension preferences to see if it resolves this issue?