Hi,
    I have the following default config file in /etc/default/grub, and I have issued the grub2-mkconfig command to update /boot/grub2/grub.cfg which confirms that it found the background image, and when I look at /boot/grub2/grub.cfg it contains the necessary command to load png support and contains the background-image command to load the referenced image file, but the background does not display when the grub menu does, what am I missing? I've had used the grub-customizer app, without doing any config changes, and it successfully load the image from the specifications in /etc/default/grub.

GRUB_TIMEOUT=100
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=false
GRUB_TERMINAL_OUTPUT="gfxterm"
GRUB_CMDLINE_LINUX="rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 rhgb quiet rd.driver.blacklist=nouveau modprobe.blacklist=nouveau
nvidia-drm.modeset=1"
GRUB_DISABLE_RECOVERY="false"
GRUB_ENABLE_BLSCFG=false
GRUB_BACKGROUND=/usr/share/sddm/themes/Galaxy-SDDM_3hu72/Galaxy-SDDM_3hu72.png

regards,
Steve