What version of horizon are you using? you may be able to switch from admin to newadmin which is html5. In regards to the process your doing its working for me so I'm not sure what your missing, I'm on horizon 7.4 and 7.10 and running flash this time works. Sometimes you may need to refresh the page, you generally don't get an error if flash isn't working though. I also see your connecting via ip, what happens if you connect via the hostname?
This is solved by creating or modifying the locked.properties file and adding checkOrigin=false then restarting the Connection Server service. This must be done for each Connection Server in your pod.