I started to use the Log Off feature much more often lately. Just now I wanted to add a new contact with a certain label but the label was not there. More than that, none of the labels that should be in the drop down list where there. All the available labels were from another character from the same account. All contacts had been moved into these labels randomly. A relog fixed this but it is quite a troublesome experience.
Troublesome enough for me to actually create a bug report: EBR-219258