Prism 5.1 guide states that "the network visualizer supports the following switches: Cisco Nexus Series switches, Cisco Catalyst Series switches, Dell switches, Arista switches".
This list has not changed in a long time and we have failed with Extreme switches as well.
Correct, it is not supported at the moment likely because parsing Juniper output has not been tested at all. I shared information to make the Juniper switch change the way it outputs the information that seemingly has worked for someone else in the past, but unfortunately that doesn't appear to work in this case. I do see that there is an internal ticket to enhance the discovery tool to properly parse Juniper output but no ETA at the moment.
We are running Arista switches, and I can only see 3 ports, not everything - no idea why.
The results are different for each switch as well - different ports visible etc.