Lables not showing up in Labels view

["Brian L Johnson"]

I've just looked in my 'Mail Back' Labels view and I can see that 5 of the  
12 or so messages listed there have no label.

If I change the missing label to 'No Label', nothing happens.

If I change the label to 'Mail Back' it acquires a Mail Back label. If I  
then change the label to 'No label', that email correctly removes itself  
from the view.

Showing everything except Trash and Period set to Forever.

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-blj-