Hi Johnathan,
The steps I mentioned earlier helps in concluding that enabling Airgroup was causing the issues on your setup.
This is due to the fact that by default it only recognizes & works with handful of Bonjour services like Airplay, Airprint, Googlecast etc.
In case you want to use/discover the devices across vlans/subnets, we need to make use of Airgroup.
Please try the following :
1. Enable Airgroup.
2. Log in to CLI of IAP & run the following commands while you are trying to use the remoteapp
show airgroup blocked-service-id
Ideally we should see the service id's used by the remoteapp which is being blocked.
3. Copy the service ID & create on new service option under Airgroup.
You can add the service id's under that service & enable it.
Then try to check if the discovery is working fine.