My fix for this was incredibly simple. I used YAWMM-Mod (not just YAWMM) to uninstall and then install the wads. Then the error didn't come up and the DLC songs are playable
The Mariocube tutorial says to use Wii Mod Lite, but that ended up being the issue.
Give that a try and let me know
I am in the exact same spot as you (just hacked my Wii, and love rock band games) and have the same issue, if you find a solution I'd love to hear it. I also followed the Mariocube tutorial and I'm dying to get the DLC working. I also see the red bar and then get the exact same message "The...
VR had the chance to integrate with existing games and tech but VR companies said "NO, I WANT MY SHIT TO BE STANDALONE AND MY GAMES EXCLUSIVE TO FACEBOOK"
Back when Oculus Rift was still starting out and being demoed around, they modded existing games to use it as a 360° immersive screen thing and that was AMAZING.
The tech isn't there for affordable power enough VR headsets at a good market value yet sadly, oculus had a good idea but didn't have enough funds for marketing iirc
But now it's "can I use my VR set with my racing games, that would be neat?" "ONLY IF YOU USE OUR DILDOSTICK CONTROLLERS AND RUN THE GAME ON OUR ANDROID-UNDERPOWERED BRICK"
These are the same type of gamers that spend $2,000 on a GPU when a $600 GPU gives nearly the same outcome which is what the market looks at for them to do spend more on unneeded bs