I often review the ‘unsorted’ list to add labels.
While clicking on the labels button allows selection of multiple labels (and then Apply Changes to save), opening the same menu with the shortcut l does not allow more than one label, because after the first label is added (by hitting return), the label menu is closed, the record is no longer unsorted and disappears from view.
A (suboptimal) workaround is to apply an unsorted label to the unsorted records which allows adding more labels.
It would be great, at least in the unsorted view, to allow label selection (but not menu closing) with a single return keystroke and then closing the menu to apply changes with a second return keystroke.