Disney+ and Max with same subscription via SharePlay on Apple Vision Pro Fails With Black Screen

Using SharePlay on two Apple Vision Pro devices connected to the same Wi-Fi network seems to fail with a black screen on the secondary device when using Disney+ and Max. Despite both devices having active subscriptions, they are logged into the same account since we are a family on the same network in the same house.

Is it incorrect to assume this configuration should work? It would seem unreasonable to require two family members in the same room to have separate subscriptions to watch the same programming.