There are many sites that refue to load correctly. Soundcloud does not load at all and assets from Canva's stock media library only load the alt text descriptions. Both show that the culprit is the cross origin requests being blocked. I have reset Firefox to factory settings, uninstalled plugins, disabled enhanced tracking prevention, etc and tested private browsing which sometimes works but seems to be inconsistent. Any guess on why Firefox would be blocking Cross-Origin Requests? These sites have worked with Firefox in the past and work on Safari on the same Mac. '''Canva''': Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://media-public.canva.com/KH7y4/MAEGv3KH7y4/1/tl.png. (Reason: CORS request did not succeed). Status code: (null) '''Soundcloud''': Failed to load ‘https://a-v2.sndcdn.com/assets/2-517dcb44.js’. A ServiceWorker passed a promise to FetchEvent.respondWith() that resolved with non-Response value ‘undefined’. service-worker.js:1:2774 Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://a-v2.sndcdn.com/assets/2-517dcb44.js. (Reason: CORS request did not succeed). Status code: (null). <script> source URI is not allowed in this document: “https://a-v2.sndcdn.com/assets/2-517dcb44.js”.