I made a minor change to your solver set-up and was able to get non-zero concentrations. See attached screenshot.
First, solve for the laminar flow study then when you solve for the species transport, click the "Values of variables NOT solved for" check box and use the final time step from the laminar flow study solution. Make sure to uncheck the "Laminar Flow" physics under the section "Physics and Variables Selection" for the transport of species study. You do NOT need to re-solved for the laminar flow because of the sequentially coupled (one-way) nature of the multi-physics problem.
See attached mph file. I, too, cleared the meshes and solution to save space.