title: Gnome Boxes on Fedora 33 fails to open
body: <p>I attempt to load gnome-boxes from the terminal (I'm running Fedora 33) and get the following error</p>
  <pre><code>$ gnome-boxes
  
  (gnome-boxes:3194): Gtk-WARNING **: 12:34:57.343: GtkFlowBox with a model will ignore sort and filter functions
  
  (gnome-boxes:3194): Gtk-WARNING **: 12:34:57.344: GtkListBox with a model will ignore sort and filter functions
  
  (gnome-boxes:3194): Boxes-WARNING **: 12:34:57.904: libvirt-machine.vala:83: Failed to disable 3D Acceleration
  
  (gnome-boxes:3194): Boxes-WARNING **: 12:34:57.913: libvirt-broker.vala:70: Failed to update domain 'fedora33-wor-2': Failed to set domain configuration: XML error: Invalid PCI address 0000:04:00.0. slot must be &gt;= 1
  
  (gnome-boxes:3194): Boxes-CRITICAL **: 12:34:57.916: boxes_vm_importer_get_source_media: assertion 'self != NULL' failed
  Segmentation fault (core dumped)
  </code></pre>
  <p>My system:</p>
  <pre><code>$uname -a
  Linux localhost.localdomain 5.9.16-200.fc33.x86_64 #1 SMP Mon Dec 21 14:08:22 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
  </code></pre>
  <p>I don't whether it's related but I recently updated from kernel 5.9.11 directly to 5.9.16 (haven't used the PC in question for some weeks) and before gnome-boxes was working as normal.</p>
  <p>Please advise how I can restore gnome-boxes - I have some virtual machines that I need to access...</p>