This is a minor change, but apparently a not well-publicized one. We have two entities, one that owns the trademarks and copyrights, and is the manufacturer, and another set up to be the Amazon seller. So, there needs to be a grant of this authority, via emails sent and acknowledged.
(The Amazon seller entity is a “disposable” LLC, that, in the event of Amazon deciding to terminate the relationship for some vague reason, is easily replaced with a new arms-length seller LLC).