Hello,
I noticed some issues with notifications.
Empty notifications
When I disable the chat the chat related notifications will be hidden but it leave the empty placeholder on user menu. On notifications page the notifications still appears.
I have some chat notification on the top.
If I disable the chat the chat related notifications will be empty.
Broken notifications page
Unfortunately I have no repro for this. I noticed this on (All) tab on notifications page in my admin account. On my notifications page or when I go to the user menu chat tab.
In safe mode with (disable all plugin) setting the notifications page works. I think because it disable chat too.
On notifications page 
On user menu chat tab the notifications seems appear (maybe not all) but get an error
Chat empty state message
I think the notification preferences link should go to /preferences/chat instead of /preferences/notifications since there is no chat related settings except allow chat direct messages on notifications page.
Thank you 