In macOS 10.12.3, Safari 10.0.3, the mems are invisible. I can click the < and > buttons, but the space in between is empty. Once I choose a mem by pressing the Next button, I can see the mem I just “chose”.
I don’t know when the problem started occurring, but I noticed it about a week ago. I even tried creating a new user account, to make sure the problem is not in my setup.
Cheers