I just installed Proxmox today and while I can't help you with you current problem I can war you of another one that you will soon encounter. When installed from a USB drive there is a know issue of grub being written on the USB drive instead of the selected hard drive. There's no error message but when you reboot after the install nothing happens. I temporarily solved the issue by booting from a Super Grub2 disk. Booting from a live USB, chroot-ing into PVE and manually installing grub should be a more permanent fix. That or installing via CD or Debian.
vagy:
https://www.reddit.com/r/homelab/comments/291y76/fresh_install_of_proxm…
már megírtam win-en három különböző usb flasherrel, meg macos alól is. Lehet az zavarja meg, hogy a freenas pendrive-ja is bent van a vasban +2 hdd +1 ssd. Ez amúgy egy UEFIs szépség, lehet az a baja, még odáig el sem jutottam, hogy a RAID controller legyen a baja, amire valaki panaszkodik a proxmox fórumon.