Z-Buffering issue in NFS3 Glide

[EriolGaurhoth]

VirtualBox v7.0.10 r158379
Host OS: Windows 11 Pro x64, Intel i7-11800H
My VM: Windows 98 SE, 512 MB RAM, 128 MB VRAM, AC97, 32-bit desktop color depth, AVX not enabled

I've been tinkering around with Need for Speed III, the DirectX rendering version works great - contrary to what the 3D Setup warns when selecting an "unknown" graphics card. However, the DirectX version maxes out at 800x600 resolution, so I edited the registry settings for the game to make use of glide, which allows me to run in full 1024x768.

However, with Z-buffer turned on, all the color in the game is this very washed-out white-looking mess. Turning Z-buffer off fixes this. I'm not sure if it's a bug with the game itself or with SoftGPU, but it is certainly odd behavior.

With Z-Buffering On:

With Z-Buffering Off:

It should also be noted that I run my Windows 98 VM in thousands-of-colors natively, as I know anything 3DFx doesn't like 32-bit colors. I thought that might have something to do with the problem, but in this case, manually setting to the correct color depth doesn't fix it.