1. Add CD/DVD Drive with no ISO
Can you see the drive?
2. Replace space with _ in your ISO
Will this work?
3. edit /etc/pve/qemu-server/101.conf from CLI
add: ide0: cdrom,media=cdrom
I think it is the space in the ISO name
Search the PID of the machine with:
ps aux | grep "/usr/bin/kvm -id VMID"
Kill it with:
kill -9 PID
Start your machine again with:
qm start VMID
And look if you can stop your machine in GUI or CLI
CLI: qm stop VMID