  In this paper, we conduct a search in the latest large-scale structure
measurements for signatures of the dark matter-dark radiation interaction
proposed by Buen-Abad et al. (2015). We show that prior claims of a detection
of this interaction rely on a use of the SZ cluster mass function that ignores
uncertainty in the mass-observable relationship. Including this uncertainty we
find that the inferred level of interaction remains consistent with the data,
but so does zero interaction; i.e., there is no longer a detection. We also
point out that inference of the shape and amplitude of the matter power
spectrum from Ly$\alpha$ forest measurements is highly inconsistent with the
predictions of the $\Lambda$CDM model conditioned on Planck CMB temperature,
polarization, and lensing power spectra, and that the dark matter-dark
radiation model can restore that consistency. We also phenomenologically
generalize the model of Buen-Abad et al. (2015) to allow for interaction rates
with different scalings with temperature, and find that the original scaling is
preferred by the data.
