We need more information. If all of your mdns clients are wireless, the "autoassociate" option will only show those devices to users who are connected to the same ap, or an AP adjacent to those APs. If the mdns clients are wired, you will need to manually configure the wired mac of those mdns clients to what AP they should be associated to, to work.
The best practice is to only allow airplay/mdns advertisements for limited amounts of services (printing and airplay, for example), because (1) there is a finite limit to the number of devices that can be managed per platform and (2) You don't want users to wade through hundreds of devices when they are just looking for a printer.