The workaround has two parts:
1. Copy the .iso to your home directory
2. Change the file extension to .img
The first part is the key. If you now run usb-creator-gtk, it should automatically see the ".img" file and pre-select it. If you use the "Other..." option to find the file, it will fail.
I think the "isoinfo: Unable to find Joliet SVD" is a red-herring
The workaround has two parts:
1. Copy the .iso to your home directory
2. Change the file extension to .img
The first part is the key. If you now run usb-creator-gtk, it should automatically see the ".img" file and pre-select it. If you use the "Other..." option to find the file, it will fail.
I think the "isoinfo: Unable to find Joliet SVD" is a red-herring
Just did this in Ubuntu 20.04.6 LTS