[Bug]: IDAKLU solver sensitivity calculation

[anoushka2000]

PyBaMM Version

22.8

Python Version

3.9

Describe the bug

Sensitivities with respect to Negative electrode diffusivity [m2.s-1] and Positive electrode diffusivity [m2.s-1] found by IDAKLU solver are 0 for SPMe model with Chen 2020 parameter values, C/10 constant current discharge

Steps to Reproduce

import pybamm
import numpy as np

model = pybamm.lithium_ion.SPMe()

param = pybamm.ParameterValues("Chen2020")
param["Negative electrode diffusivity [m2.s-1]"] = pybamm.InputParameter("Ds_n")
param["Positive electrode diffusivity [m2.s-1]"] = pybamm.InputParameter("Ds_p")
param["Electrolyte diffusivity [m2.s-1]"] = pybamm.InputParameter("De")


simulation = pybamm.Simulation(model, parameter_values=param, solver = pybamm.IDAKLUSolver())


t_max = 60*60*10
t_eval = np.linspace(0, t_max, num=(t_max//2))

solution = simulation.solve(t_eval,
                            inputs={ "Ds_n": 3.54e-14, "Ds_p": 1.01e-13, "De": 3.71e-10}, 
                            calculate_sensitivities=True)

np.unique(solution.sensitivities['De'].flatten(), return_counts=True)

# resulting in all sensitivities = 0
np.unique(solution.sensitivities['Ds_n'].flatten(), return_counts=True)
np.unique(solution.sensitivities['Ds_p'].flatten(), return_counts=True)

Relevant log output

No response

[martinjrobins]

This is an issue with the transfer of sensitivity data from C++ back to python when the simulation stops early due to an event. I've opened a pr in #2337 to fix this