Hey there! Just wanted to add that there also seems to be an issue with NKIT.ISO files. It brings up the same error on my end when I try to load Twilight Princess on the official play store version of Dolphin from the latest version of Launchbox.
I would use Dolphin MMJR, but this is another case where the game seems to run better in the official Dolphin app for me.
Currently running on Android 10.