Pro/E has had a problem with this since I've been on it (V.15). It will not force a second regen if needed, it must be done manually. This shows it's ugly head in relations, as you've seen regenerating instances, and some other areas. I had done something really neat with a type of "hoffman box" I designed where I had to show 4 different electronic configurations, and instances of all 4 with the door open and closed for the drawing. Now, we had a ground wire attached to the lid from the electronics. The 3d trajectory (intersection of 2 curves) I made worked fine with both the door open, and door closed......except the second regen would not work until I manually loaded the instance of the assy first before I opened the dwg. If I tried to just open the dwg, the wire was hanging out in space. Until they fix this serious issue, we're just going to have to use the Pro/WORKAROUND and Pro/FANITY modules.....