When I try to add a contact to Lists, I am able to scroll down only as far as lists that begin with the letter "D". It doesn't happen all the time but it happens often enough to be annoying. I just rebooted too. I don't understand why it doesn't show me all my lists.
Thank you for providing this screenshot! It has definitely helped us to understand exactly what is happening. This experiencing is something we are troubleshooting further. Is this happening in more than one browser? Cases where customers are unable to view all lists, there are a few workarounds that have worked in the meantime. These workarounds include: exiting and re-entering the contact, marking a list that is not appearing as a favorite, or even selecting ALL lists to be added.
Using the star option will mark your list as a favorite on the main contacts page. This will make that list appear at the top of the selections in an individual contact. While applying all lists will show all checked lists in your contact's selection box.