"policies": {
   "ExtensionSettings": {
     "*": {
       "blocked_install_message": "Error message to display",
       "install_sources": [
         "https://addons.mozilla.org/"
       ],
       "installation_mode": "blocked"
     },
     "uBlock0@raymondhill.net": {
       "install_url": "https://addons.mozilla.org/firefox/downloads/latest/ublock-origin/latest.xpi",
       "installation_mode": "allowed"
     },
     "{a7589411-c5f6-41cf-8bdc-f66527d9d930}.xpi": {
       "install_url": "https://addons.mozilla.org/firefox/downloads/latest/matte-black-red/latest.xpi",
       "installation_mode": "allowed"
     }
   }
 }

I am creating a policies.json file to block all Add ons except ones specified specifically. I have figured out how to do this for normal extensions, but I have run into issues when applying the same principle to themes. What am I doing wrong? Here is my sample code that works to allow the ublock add on, no problem, but it is not working to allow the matte-black-red theme: { "policies": { "ExtensionSettings": { "*": { "blocked_install_message": "Error message to display", "install_sources": [ "https://addons.mozilla.org/" ], "installation_mode": "blocked" }, "uBlock0@raymondhill.net": { "install_url": "https://addons.mozilla.org/firefox/downloads/latest/ublock-origin/latest.xpi", "installation_mode": "allowed" }, "{a7589411-c5f6-41cf-8bdc-f66527d9d930}.xpi": { "install_url": "https://addons.mozilla.org/firefox/downloads/latest/matte-black-red/latest.xpi", "installation_mode": "allowed" } } } }

"{a7589411-c5f6-41cf-8bdc-f66527d9d930}.xpi": {
   "install_url": "https://addons.mozilla.org/firefox/downloads/latest/matte-black-red/latest.xpi",
   "installation_mode": "allowed"
}

"{a7589411-c5f6-41cf-8bdc-f66527d9d930}": {
   "install_url": "https://addons.mozilla.org/firefox/downloads/latest/matte-black-red/latest.xpi",
   "installation_mode": "allowed"
}