Unable to Claim Reward — GraphQLError: chain node running in readonly mode

When attempting to claim my reward in the ArcBlock/Sphere app, the system displays an error message saying “GraphQLError: This chain node is running in readonly mode” and the claim action fails. The countdown timer and reward interface appear normal, but pressing “Claim Reward” does not trigger the transaction. This issue prevents me from claiming my reward and appears to be caused by the backend node being in read-only mode, likely due to maintenance or a routing issue. Please investigate and ensure the claim function routes to a writable chain node or displays a proper maintenance message. Device: Android, stable network connection; issue persists after restarting the app.