On upgrading to 1.6, I have exactly this issue. The Auth Manager is absolutely fine and nothing has changed since I last ran my tests in 1.5. The initial post contains nothing useful, other than an acknowledgement that there is a problem.
Obviously, I can waste my time trying to find a solution for this. Or I can try to revert back to 1.5, which is probably going to be easier and quicker.
In case anyone still needs to know, here's my solution (in 1.8, which I presume is much the same as 1.6 in this regard):
On the Projects tab, select "Auth Manager".
On the window which pops up select "Auth Manager" tab
Here, I found that my root TestSuite was set to "No authorization" and all of the TestCases used the profile that I had set up (with TestSteps inheriting). I changed the root to use the profile and this was inherited downwards.
This fixed the problem (although needed to be repeated for each Environment).
