Identify or spatial selection operations may fail to return any data when the selection point is nearer the midpoint of a long line segment and further from the vertices of the feature.
This is expected behavior for data stored in a geodetic coordinate system in an Oracle Spatial database.
Data stored in a geodetic coordinate system follows the curvature of the earth. Over large distances, this curvature is great enough that the search window is not proximate to the line; you are clicking or selecting what looks to ArcGIS to be a straight line (in Cartesian space), but using Great Circle paths, the data is actually a curved line in the Oracle Spatial database. Therefore, the spatial query window does not cross the actual path of the line and does not return any rows.