While their might be an occasional 'hiccup' when it comes to computing hidden line displays in a Drawing view, and what you're showing could well be that, there's also the possibility that the two faces which defines that particular edge is NOT exactly tangent (i.e. smooth). As a 'quick & dirty' test go back into modeling and try creating a small Edge Blend selecting that edge. If the edge is truly tangent (i.e. smooth) the system will NOT allow the creation of the Blend feature. However, if it does, then the edge was not tangent in the first place.
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA Siemens PLM: UG/NX Museum:
To an Engineer, the glass is twice as big as it needs to be.