oh boy, you are right!
I downloaded the incorrect ISO from Debian. (what a noob, lol)
It is working now. Thank you for your help.

@olivierlambert Sure thing,
Here is the ISO SR and the 2 ISOs I have uploaded.

The Win10 ISO works fine.

I am having trouble getting my first VM to boot from the ISO I downloaded.
ISO is Debian 12, XCP-ng is a fresh install on my server, Xen Orchestra is a fresh install as well with my 30 day trial license.
ISO storage has been created and Debian ISO has been uploaded to this storage.
I have created a new VM with the Debian 12 template. The only I changed was the boot order and disabled network boot.
Once I start up the VM I get an error, "Boot device: CD-Rom526MB Medium detected - failure: could not read boot disk"
I removed the VM a few times and created a new one but still not working.
I have even re-downloaded the ISO from Debian a few times as well and uploaded to ISO storage, but that has not fixed this issue either.
Not sure what I am missing.