I made a build of CKEditor 5 based on Decoupled document on the official website: https://ckeditor.com/ckeditor-5/online-builder/

But 2 buttons do not work in this build: Special characters (empty list) and Source.

The build ckeditor5-41.3.1-tnhriujfhl8s.zip is here or you can create build youtself: ckeditor5-41.3.1-tnhriujfhl8s.zip

Why are the buttons not working as expected and how can I fix them?

Thanks!