Earlier quoted context omitted.
I must have misremembered, then; my apologies. Perhaps it was a Win98 vs Win98 SE difference?
Maybe it also required GPU drivers to be installed? I clearly remember the gradient bars.
However, now that I think about it, such gradient bars must have required at least 16-bit color to work without dithering, so they were probably turned off by default for anything lower. And, at the time, budget video cards had limits on color depth in higher resolutions - e.g. for S3 Trio, if I remember correctly, you got a max of 24-bit color at 800x600, 16-bit at 1024x768, and 8-bit at 1280x1024; you could see the color depth combo box switch as you dragged the resolution slider. So I probably just ran it at 8-bit depth then.