Hey, it's been a while but I tried poking around with some of the settings. There isn't a clear error and I think it's some sort of old graphics related issue. I tried disabling a setting specific to Windows 7 ("Use DXGI flip model swapchain") in case that fixes it. I also made it so you could freely resize the window in the build below as well -- hopefully either of those fix it.
Here's a link to the build: https://drive.google.com/file/d/1eNKnlnot_NaPoKy3rLjmbLHvbU4NnsOo/view?usp=drive...