The spectro-spatially stacked spectra of the ARKS targets where no CO emission was detected. In each plot, we show both the spectrum shifted with the disc’s inclination i and also with i + 180°, to eliminate the degeneracy between rotational direction and inclination. The black solid line indicates the stellar velocity, in the barycentric frame, which is where we would expect to see a peak if gas was detected in the system. The black dotted lines indicate the region of V_⋆ ± 3.5 km s⁻¹ which was integrated over to calculate the line flux.