I'm curious about Local vs. Existing as well.  I'm troubleshooting a report view ACL that seems to only exist in our production instance (still on vancouver) and not in our sandbox (upgraded to Washington already).  it's marked as Local, but the current version is stuck on an older 'default' and not on what should be a more updated version from the application.  there are no updates on the updates related list and the ACL itself shows created by 'service.now' and updated by 'admin'.  don't think i've ever seen the user 'service.now'.  And comparing the 'current' version to most recent from the application removes the 'local' value to null in the field.

before I open a HI ticket- any thoughts?