Tried all three and it didn't work. New account still gave me the ISOEXTRACT error. Running as admin or turning off virus protection didn't change anything.
Edit: Y'all I think I got something.
I happened to download a wbfs copy of Kirby's Return to Dreamland while grabbing all the ISOs, and I decided to test it out, and IT WORKED. It's completely functional on my WiiU.
Gonna test it out with other wbfs games and see if those work over ISOs.
Edit 2: Okay so maybe the problem is that I've been using nkit iso files and not just plain iso?
Edit 3: Yeah the problem is DEFINITELY the nkit iso files. Earth Seeker was an iso file while all the other games were nkit.
Pretty proud of myself for wading through this. Hope this helps other people with the same problem.
Edit 4: Anyway now that I've solved that problem, I was wondering if anyone knew why Killer7 has duplicate enemies when injected onto the Wii U? I can't find any way to fix that other than it apparently being due to the width of the screen, but I tried forcing it in 4:3 and it still didn't work. Also there's a glitch or something where the characters will constantly reload.