We are having the same issues with our brand new 70-inch. The rest of our Samsung TVs work with the app. If there is a known solution other than a full factory reset, let us know. According to some consumers, this is a temporary fix and doesn't fully address the issue.
i find it frustrating that the Samsung response would be to contact the Disney plus development team. As consumers, we don't have access to those contacts where Samsung product managers and consumer response personnel would.
You can locate the app developer's information in the app store. Just go to the app store, scroll down and the app developer's information on how to reach out to them will be there.
Hope this helps