BLOAD into 320x200 8bpp fails on certain VGA cards in DOS

[keenmaster486]

My machine:

Intel 486DX2/66
Cirrus Logic CL-GD5428 VLB VGA

Using FB version: 1.10.1

What I'm trying to do: set the video mode and use BLOAD to display a small 8bpp palletized BMP file

Example:

#lang "fb"
#include once "fbgfx.bi"

screenres 320, 200, 8, 1 'if I set the height to 240, it works fine
bload("TEST.BMP")

while inkey$ <> "": wend
while inkey$ = "": wend

Where it works: DOSBox, 86Box set to any VLB card except for CL-GD54xx where xx is 28 or lower

Where it does not work: 86Box with video card set to any 28 or lower Cirrus Logic card, and my real machine

Modes I tried:

256x256 8bpp (not sure how this mode even exists but it works on the real machine)
320x200 8bpp (FAILS on real machine, works elsewhere, and 86Box with CL-GD54[<=28] can't even set the mode)
320x240 8bpp (works on real machine, assuming this is using ModeX driver)

The failure consists of a blank screen with some type of stack trace being faintly displayed at the top in a shade of gray barely distinguishable from black, in a "font" so small and blocky it is impossible to read.

I have tried using both HIMEM and JEMMEX as memory managers to no avail.

My 86Box VM is set to the same exact specs as my real machine. If I select a later CL card, such as CL-GD5429, then it works.