You have content, meta, and code folders?
You have the folders like this?
SD:/wiiu/games/TITLEGAME (XXXXYY)/content <- Game Sound, Data, etc.
SD:/wiiu/games/TITLEGAME (XXXXYY)/code <- RPL and RPX (app and cos)
SD:/wiiu/games/TITLEGAME (XXXXYY)/meta<- Game Icon and whatever...
AND...
SD:/wiiu/saves/TITLEGAME (XXXXYY)/c
SD:/wiiu/saves/TITLEGAME (XXXXYY)/u
You format is FAT32?
What type of SD Card are you using?
Is a fast loading SD Card?
DarkUmbra have a bad checksum for Wii U ISOS
And... you are using the lasted Loadiine Version and Miimaker mode or SSB4 Mode?
Are you using the Update Data Folder in the game? (NOT INSTALLED IN THE NAND) IN THE SD CARD!!
EDIT; Sonic Boom is working with MiiMaker Mode.
Just Dance 2016 its working in MiiMaker Too, so you problem is the bad checksum of you game or you put something wrong in the folders.