I know this is an old thread, but it is left unanswered.
Try escaping additional quotes: GRUB_GFXMODE="\"1400x1050;640x480\""
It will produce extra quotes in grub.cfg:
set gfxmode="1400x1050;640x480"
This is how I got it to work.
I know this is an old thread, but it is left unanswered.
Try escaping additional quotes: "\"1400x1050; 640x480\ ""
GRUB_GFXMODE=
It will produce extra quotes in grub.cfg:
set gfxmode= "1400x1050; 640x480"
This is how I got it to work.