Hmmm ... for factory ownership, if ye have taken that factory's province, several things are easily seen :
1] Using 'tag (`) ' into Bozo's screens, on equipment page, a factory went red, slashing the CF, WF, and/or Shipyard production ; Strategic bombing also counts here .
2] On infrastructure page, the factory count of that State is reduced by a number [ f/x > f-1+/x ] .
If your ground forces occupied this factory's province, it should show up on your building page, needing repair; regardless of that State's overall status in ownership .
I could be wrong here; but I don't think so .