Dear Gusthavo,
The script ldos = kwant.ldos(syst, energy=0.8, params=dict(k_x = 1.7)), provides you the ldos for a given energy but not for specific kpoint.
To do so you need to get the indices for those allowed_kpoints you are looking for (condictions).
For instance, you might use
prop_modes, _ = flead.modes(energy=0.8, args=[params])
momentas_allowed = prop_modes.momenta[np.where(condictions)[0]]
inco_wf = kwant.wave_function(fsyst, energy=0.8, args=[params])(0)
wf_for_related_allowed_kpoints = inco_wf[momentas_allowed, :]
kwant.plotter.density(fsyst, wf_for_related_allowed_kpoints, cmap='gist_heat_r')
As Abbout said, If you share the script, it would be better.
I hope this help
best