You were able to post in STH, so perhaps you had to switch to a non-mobile device to achieve this, I don't know. However, you should be able to see and reach all forums. They remain visible and available to everyone on all platforms (it wouldn't disappear from mobile and NOT from desktop at the same time). Of all the issues we have, this isn't one that we're aware of.
Can you explain more what you are experiencing? Any error messages?