Adding a 5th Player Character causes an interface issue in selection menu

[Newbiespud]

Decided to start my foray into modding by adding a new playable character like the Shel example. Managed to get them into the main menu alongside Shel, but when I go to click on them something odd happens. The other characters slide and slowly disappear as the selection zooms in, but in the case of having 5 characters and clicking on the 4th, the 5th character (in my case Shel) slides to the left and remains active for a bit. If I keep my mouse still, Shel passes under it just as she's about to disappear, then the menu swings back and leaves me where I started, only with Shel highlighted. If I move my mouse to the left with my new character after clicking on them, that doesn't happen.