Not sure what happened, but I once used this method several times before for PS Vita without any issues and now it doesn't work. My guess is that the new PSVita importing feature that was recently implemented has messed this up somehow. Can anyone help because every time I try to import multiple .txt files, it comes up empty, as shown in the screenshot below. I've also tried importing the game folders, the individual eboot.bin files and none of these methods worked either.
Another update: Can confirm that this is an issue related with the latest versions of LaunchBox. I just tried an older version (13.18) and the importing method for PSVita games works fine, but there's basically no way to manually import PSVita games with the latest versions of the program