Hi all!  I had a co-worker run into a strange issue today with a legacy assembly and I'm not sure why it's happened or how to fix it.  I've never seen this before!  This assembly is fully constrained with coincident and concentric mates; however, the nut shown highlighted, does not get moved to it's coincident mate location (instead it hovers about 10mm away, there is no offset specified), shown on the left.  Additionally, you can select the nut and it turns a strange purple color, shown on the right.  The part then gets a handle and you can move it up and down axially along the concentric mate!  Additionally, when the nut is selected, the entire ribbon (except for Instant3D is greyed out).  When you open up the "Mates" feature to add a new mate, the nuts return to the "correct" position as intended with the mates.  Has anybody run into this issue before?  When I created a fresh assembly with the same parts, I could re-mate them no problem, so I'm assuming it has something to do with the assembly settings.  We are currently running SW2020.  Assembly is attached for your reference!