We are getting reports of users not being able to login on the ACS Network. When you log in on www.acs.org or on communities.acs.org, you get pushed to the SSO-error.jsp page which asks you opt in or check your opt-in status. You are already opted in, so you get caught in a loop. It is my understanding that it doesn't help to try and reset your opt-in status as per (Login Issue - What to do if the ACS Network doesn't recognize you.)
If you are having this problem, please try the following:
For Firefox, open a "New Private Window" (access through menu on the right)
For Chrome, open a "New Incognito Window" (shift-ctrl-N on Windows)
In many cases, this will allow you to login. Sometimes just using a different browser will work as well.
It appears that not everyone is experiencing this issue, but recognize it is very frustrating for who do. Please feel free to comment below as any input from users helps us better diagnose the problem. We are working with our technical team to remedy this issue.