I have a Mobility Express configuration. The controller is AP 3800 with 8.10.121. When clients are connected to the controller they can find all the Airprint printers, but when they are connected to other subordinated APs (9100, 1850) they can not find all the printers, just some of them.
The printers and the clients are all in the same vlan
Please try to follow the Deployment Guide below to see if that helps. Though it is developed for FlexConnect Bonjour deployments, however the configuration guidelines remains consistent for Mobility Express: