Recently the Notifications box (which drops down when you click the bell in the top right) has changed design and no longer shows me any notifications. Even when I know I should have notifications, the box is empty.
However, when I switch to one of my other accounts, I get notifications in the box as expected (still with new design):
If I go to Google+, the notification box uses the previous design and properly shows my notifications:
If I open YouTube in Chrome, it shows me the previous design and properly shows my notifications.
In summary, when I'm on YouTube in Firefox with this specific account, my notifications do not show. If it's browser specific, why is it working when I switch to another account? If it's account specific, why is it working with the same account on Chrome?
Best Answer
YouTube is unintegrating Google+, and since the previous notification bell was part of Google+, it had to go. There was a brief period in which users could switch back and forth between the YouTube and Google+ versions by clearing cookies because it wasn't rolled out 100% then, but this fix no longer works. The current workaround that is using Google+ to view notifications will also stop working in the near future.
If you don't see the notifications you're expecting, make sure that you have comment reply notifications enabled on https://youtube.com/account_notifications.