Ticket 3548 created for this issue and David A has confirmed that is a real issue. Work around is to install Air-Boot for now.
Hi
It is good to know that David A replicated the issue and confirmed it.
I did a quick test here:
1) Created a VM in VirtualBox 7.0.10 (Windows Host). Selecting Standard ArcaOS choosing the default settings.
2) 1st Boot, attached the 5.1.0 Image (I like to use the little CDROM icon in the bottom of the started VM to mount the ISO), the menu displayed
without "Boot from hard disk". (Boot_001.png)
3) Went forward with the install and it tells me I have an issue with the disk that needed to be fixed. I select to fix the issue and choose "MBR". Reboot.
4) 2nd Boot , the menu displayed
without "Boot from hard disk". ( also Boot_001.png)
5) Continued forward and created the boot partition C: (Save changes) ... and stopped there and rebooted without installing ArcaOS.
5) 3rd Boot, the menu now shows "Boot from hard disk". (Boot_002.png).
I was not able to reproduce the issue here. I'm still can not get what is the difference on your system/configuration Eric.
Regards