Ah, happened to mii once to. You have to turn of the Inkay plugin from the aroma plugins menu, then exit the plugins menu. You're Wii U will reopen the home menu and then you can update them. Don't do the thing where you put in your username during the update, it won't take pnid.

If you're on 3DS, just switch back to NNID, and update through the EShop. It's still open for updating and redownloading, if you wonder.