I have searched this one and not really found a fix to this. I have an assembly called ASSY1.  I insert part P1 and constrain it to ASSY1's coordinate system.  At this point, ASSY1 is fully defined.  I then insert P2 and constrain it to P1 using 3 orthogonal faces on each part.  At this point, ASSY1 is fully defined.

I then Linear Component Pattern P2 in 2 directions with one skipped instance.  At this point, ASSY1 goes "Under Defined".  There are no ( - ) symbols in the Assembly Navigator and I have tried rebuilding.

Any thoughts?  I am using SW2015.  Thank you.