Geometry faces glicthing and disappearing

Hello, I’m a newbie using Unreal Engine, I’m taking a course learning how to do scenario whiteboxing. For some reason, I was doing things normally, only suddenly, some faces are disappearing for no reason. No, I’m not accidentally deleting faces.
So I recorded a video detailing this glitch. I’m Brazilian, but I suck at English, so forgive me for my bad pronunciation in the video
My graphics engine is from 4.26.2, however, as I’m using a project borrowed from them (yes, they required us students to do this), which is based on version 4.16. I emphasize this because I don’t know if it influences anything

Ryzen 5 3500X
16GB of RAM 2600mhz
256GB SSD Storage
1TB HD (Where my projects are saved)

Yeah, my gpu is kinda weak, I know.
So what’s supposed be the cause?