[FIXED] [CoL] Unable to complete Meddlin' and Peddlin' errand

I had this problem at first too! used the same two people: Michael B and Kim G. 

I just deleted the errand, restarted it by asking Agatha again, and got it to work! I invited them both to a different lot (so I could keep them close) gave them roses and RIGHT AWAY was able to convince them to flirt with the other person. 

So maybe as long as you don't load screens or have a sim leave and return between getting the rose and encouraging to flirt it should work!