I had this issue when SNTC 3.5 was first released. This is what TAC advised. It cleared my issues. It seems the language setting was the one that was critical.

Regards, Tim

Advice from TAC

1.Log out of portal using Logout function

2.Clear cache

3.Clear recent history and cookies

4.Login to SNTC portal

5.Select English or language required as the language choice (do this even if you have your language set)