Once I have checked a contact - nothing - can't move to new list, can't delete... what's the point. Contact Us?? That tab doesn't work, thanks. Edit Image - oh no, not here.
Is this happening with one particular contact, or all contacts? Are you receiving any error messages? After troubleshooting this further in your account with a test email, I was unable to replicate this same experience. What browser are you working in? Does this happen in more than one browser or a private/incognito window? If you have not yet tested your browser this is a great first step we suggest!
As for not being able to access our "Contact Us" sidebar, this is something we are also continuing to troubleshoot. Does this issue occur when browsing in incognito? As a workaround, we suggest attempting to access this sidebar under a different tab of your account such as: Campaigns, Reporting, Sign up Forms or Integrations.