Ok, if you have the PWA installed for the community, the notification permissions will be in that under app settings. If you're just using it on web, it'll be in the browser settings. First port of call, I think would be to double check and potentially reset those, so it can ask again and re-set them.
Beyond that, it could be a bug within the community, potentially. I've seen the odd one mentioned on their community over recent months, so I can raise a ticket with them and ask the question, assuming your permissions are all set etc.
If you're using the community in the browser, I'd probably also recommend clearing cookies/cache for the site and logging back in again, just to see if it's that.