I am having the exact same problem. I have tried several times, each time getting a new authorisation code but once Nessus gets to initializing plugins then it keeps looping endlessly.
I have tried this on both a NAT and Bridged network but I am still having the same issue. There was a fix for this for 5.2.2 but now with the latest release v6.3 as of 30/03/2015, it keeps looping.
- I am using Kali Linux v 1.0.6 64bit, Windows 7, 8Gb ram i7
Can someone from Tenable please help???