I'm wondering if adding "video=HDMI-A-1:1920x1080M@60" to kernel boot params in syslinux.cfg would help? Using the GBM (non-legacy) image would be preferred over the X11 (legacy) one.
please see this post RE: LibreELEC (Nexus) 11.0.3 and RE: LibreELEC (Nexus) 11.0.3
Does AMD Ryzen 3 3200G / Ryzen 5 3400G cannot use the GBM (non-legacy) image?
We'd appreciate it if we could use it.