Unproxyable

The attempted call is not permitted by the registered proxy type's call filter. Check which proxy_type the sender holds in the real account's Proxies entry and whether that type's InstanceFilter allows this specific call.

Declared by the Proxy pallet; it classifies to the semantic code not_authorized.

Remediation

Sign with the key or origin that owns the target object, then retry

The same explanation is available in the terminal: btcli explain Unproxyable.