Hi MrO,
Seems like you want to use APM for authentication and are using the scenario noted in the DG on page 4, "BIG-IP APM/LTM with proxied PCoIP connections using Connection Servers only".
Make sure the connection servers are using the settings noted on page 6, "Modifying the View implementation if using Connection Servers only". (uncheck all proxy settings)
The error in the log indicates the horizon view remote desktop profile "VMware-View__remote_desktop..." is unable to communicate to pool View__pool_0. Could be that the remote desktop profile is not setup correctly and the BIG-IP is incorrectly communicating to connection server pool.
Since you are using ssl offload and appear to be using iApp to configure your BIG-IP, verify you are using the latest horizon view iApp and is using the following settings:
Do you want to deploy BIG-IP Access Policy Manager?: Yes
How should the BIG-IP system handle encrypted traffic? (SSL offload)
The iApp created (443) virtual server will have both a client and server ssl profile (even though it is ssl offload...) and the iApp produced remote desktop profile should have "Server Side SSL" option un-checked.
If all this seems accurate, I would run tcpdump on the big-ip to diagnose why big-ip communication to the connection server pool is failing.