Error when calling flow_box with variable TI

I got an unexpected error making a flow_box with spatially varrying TI:

from py_wake.examples.data.ParqueFicticio import ParqueFicticioSite
import numpy as np
from py_wake.site import XRSite
from py_wake.superposition_models import LinearSum
from py_wake.rotor_avg_models import RotorCenter
from py_wake.examples.data.dtu10mw._dtu10mw import DTU10MW
from py_wake.deficit_models.gaussian import BastankhahGaussian

# prepare data
turbine = DTU10MW()
site = ParqueFicticioSite()
site.ds['x'] = 10 * (site.ds.x - site.ds.x.max() + 1000)
site.ds['y'] = 10 * (site.ds.y - site.ds.y.max() + 1000)
site = XRSite(site.ds)
wfm =  BastankhahGaussian(
        site,
        turbine,
        k=0.04,
        ceps=0.2,
        use_effective_ws=True,
        superpositionModel=LinearSum(),
        rotorAvgModel=RotorCenter(),
    )
x = [0, 1248.1, 2496.2, 3744.3]
y = [0, 0, 0, 0]
ti_interpolated = site.ds.ti15ms.interp(x=x, y=y, h=turbine.hub_height())
TI = np.array([ti_interpolated.isel(x=i, y=i).values for i in range(len(x))])

# can't make flow box with variable TI. Works when TI=0.1
res = wfm(x, y, TI=TI, wd=site.ds.wd)
res.flow_box(x=np.linspace(0, 100), y=np.linspace(-100, 100), h=[200])

The error is:

AttributeError: 'LocalWind' object has no attribute 'TI_ilk'

This error goes away if I use a constant TI