Problems running a simple circuit on IonQ through Qiskit

Question

I am trying to determine the effect of decoherence into a system (without loss of generality we can take a 1 qubit system) prepared into the initial state |0>, and put it in presence of the noise environment. It means that the qubit just undergoes decoherence and then is measured, no gates are applied on the way .

When I tried to do this using the simulator and qpu of IonQ the output was a message that said job incurred error, but when I execute the same circuit on the IBM platform I do not have that problem, and I can get measurements in the real devices of IBM, which take account of the effect of T1, T2 among other sources of error on the evolution of the qubits. Because of this, I want to ask the following:

1) Why IonQ cannot perform the operation that does "nothing" (no gates applied) on a system of qubits?
2) Given that the Z-gate is performed on Qiskit with zero error and time ( https://qiskit.org/documentation/stubs/qiskit.circuit.library.RZGate.html, https://arxiv.org/abs/1612.00858), does the IonQ perform the Z-gate in the same way or I should assume a non-zero error gate? Just in case there is a non-zero error gate for the Z-gate, how can I get the information of this value for each qubit?

Thanks for your attention and help.