The geometry of the knuckle does not overlap the corresponding plate edge. As a result, the edge attributes are incorrect.
Bad bounding or split operation.
What You Should Do
Separately try each of the following steps:
Right-click and select Update.
Manually correct other objects with errors associated with the object.
If the knuckle uses sketched geometry, extend it past the plate edges.
Click Recompute in the Results dialog box to recalculate the object.