Firefox people are telling me on my dedicated post on my page to this topic today for the new features -- try logging in and out, again. I did not have to in Chrome but maybe you do. Check here on my latest undervalued post lol

https://steemit.com/steemit/@barrydutton/new-feature-activated-on-steemit-in-browser-notifications-for-mentions-replies-etc-short-form-post-w-explainer-graphic