I've already seen such behaviour with proxmox USB keys while googling.
I can observe this on a new server (HPE ProLiant DL360 Gen9).
The ISO image was SHA256 checked. It was written with a good old dd. And it was rewritten again after, just to be sure it wasn't a USB key problem...
i use 20 Containers on the host, until it works without problems.
No the User have no harddisk and no cdrom
vm 100 - unable to parse value of 'sata0' - format error at /usr/share/perl5/PVE/JSONSchema.pm line 528
volume: property is missing and it is not optional
vm 100 - unable to...