Yeah, I wrote this in my article: "When you first startup the virtual machine during the runtime it will create a folder under /var/lib/libvirt/swtpm/ something like this /var/lib/libvirt/swtpm/141d5517-bb66-23b3-6373-c4288xxxxxx, you need to make sure that you copy this whole folder into the VM storage area and symlink it back on the next boot as /var/lib/libvirt/swtpm/ is not persistent."   Anyway to do a quick test (most probably its a permission issue), you could do  ln -