I got the achievement for buying all the songs from the store. So, I start playing them all. When I get all the way down the list to Thunderhorse and Trogdor I beat them and never get the Saturday Morning Award. At the time I didnt know what was going on, so I continues playing through the song hoping that if I got the achievement for beating all the unlock songs it would give me the Saturday Morning achievement as well. After I beat them all, I never got either achievement. I beat all the songs on Medium from the quick play menu. Do I have to do it the career mode? Btw, Yes We Can by Made In Mexico is NOT EVEN A SONG, ITS A BUNCH OF ANNOYING SOUNDS CRAMMED TOGETHER TO MAKE YOUR EARS BLEED!!!
I have no idea about the Saturday Morning one, but yeah, medium has to be played in career. And indeed, Made in Mexico does suck.
For the medium songs, it does have to be in career. The achievement says something like "Beat the Medium Tour" or something. With Thunderhorse and Trogdor, try them in career too. I got them in quick play, I think, but they unlocked for me.
Yeah, I did all of it in Career mode, and I still never got the achievements. I've done everything in both Career and Quick Play.