makimu That’s interesting, I watched the process and what he does is pretty identical to what Batocera does when flashing the OS.
The only difference is, they used MBR partitioning scheme instead of GPT. MBR (Master Boot Record) is the older format which has less support for newer filesystems and is generally not recommended.
The most likely case is that the UEFI on your motherboard is looking for a specific GPT table but is failing to find it, resulting in a “no operating system found” error. But with MBR, since it does not care as much about what is on it, it is able to find and boot it.
I’ll let the lead dev know about this, but I can assume the most likely response is going to be “we do not support buggy/faulty motherboards like that”. Thank you for your research though.