After removing the Username/Displayname combo some years ago, Invision have done a complete volte-face and decided that it's now insecure. Just like I did when they changed it back then. Aaaaaanyway, we're now being nagged to change the Login ID to your email address, so that's what I'm going to do shortly.
So next time you need to login USE YOUR EMAIL ADDRESS not your Displayname. N'kay?