Like Mike, just guessing without the file to look at, but my best guess is it appears to be a "0" dimension because it looks as though there are leader extensions on either side of the "0". I will bet that you can drag the dimension. and relocated the extensions
I also think it was a dimension that came from the center of the protrusion to maybe an edge and because all of them are the same, a reference point was lost and it defaulted back to the center. Thus the "0".
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Scott McFadden
(Colossians 3:23-25)