When adding by double clicking or just drag-and-drop a picture on the icon designated for pictures (under the Delete button on the right side), the formatting set under Settings is not honored. It usually goes to ISO-8859-1 and not to the encoding that I've set up (in this case UTF8).
The only way to fix this is if I add the APIC field using the "Add..." button, then the encoding is kept to what the Settings field says.
I'm using Kid3-qt (no KDE dependencies) version 3.3.0 downloaded from your PPA for Ubuntu 14.04
Hope this can be fixed.
Thanks for the report, it is now fixed in Git [6c9d96].
Related
Commit: [6c9d96]
Fixed in version 3.3.1.