Faces Disappearing

That's a missing shader. Cleaning system and video card shader cache will fix the issue (the game will rebuild them at start up). For GTX nvidia card would be cleaning those locations: c:\Users\[uername]\AppData\LocalLow\NVIDIA\PerDriverVersion\DXCache\  c:\Users\[uername]\AppData\Local\NVIDIA\  c:\Users\[uername]\AppData\Roaming\NVIDIA\ComputeCache\  c:\Users\[uername]\AppData\Local\cache\  c:\Users\[uername]\AppData\Local\D3DSCache\   Might be the same for RTX cards as well but I can't confirm.  For intel cards there are other locations and same would be for AMD.