Me and my friend completed LASO Campaign yesterday. We both headed to waypoint to unlock the emblem, it worked for him but not for me. We did the whole thing together . I hosted some missons and he hosted some too. I can’t figure out what the problem is, please help 
Usually people go to the ‘Waypoint’ section of the forum and post a list of links to each of the completed mission stats.
If I was you I’d get the links to each of the missions stats and add them to your post here. If a mod wants to move this post they can, hopefully it’ll get seen whichever board its on.
I don’t know if it makes a difference but you could try doing prologue and epilogue on coop LASO as well (from stats looks like you already tried that).
EDIT:
For your convenience:
Thank you 