1. Create a new profile in GNOME Terminal settings, rename it to e.g. 'default'. The name will be overwritten on import, you can then rename it again to what you want
This step is not necessary if you already have created a profile that is not the default "unnamed" profile.
2. Set the new profile as the default profile
3. run `dconf dump /org/gnome/terminal/legacy/profiles:/`, see that it returns output similar to this: