Put simply, the incorrect model is shown whenever WX-78 moves towards the left. Instead of the side with the exposed gear and in-tact bolt showing (the model that shows when moving left), the side with the broken down rusted bolt shows when moving both left and right (despite this model being the model that is shown only when moving right.) See files for clarity.
Both images have WX-78's left side model showing for both side models. This is the bug, as this is not what WX-78's Survivor skin should look like.
I am not sure how visual bugs are caused, nor am I aware of how to reproduce said bug. This bug happened earlier this year, around January.