My story is the same as yours, I knew this was coming because it happened last year in my corn, and I managed to get them killed with dicamba.  This year we went ahead and walked the beans, but a few of them that were too small to see are coming on now.  We have another field with a waterhemp escape, I have dead waterhemp right next to perfectly healthy waterhemp, so now we have both weeds that are resistant to roundup.  Roundup's days are pretty much over.