Not sure if it's just my account, but when I browse to https://wikitech.wikimedia.org/wiki/Special:Notifications I see:
[00fc56ad20d2079ac563d6d6] 2018-05-31 01:59:52: Fatal exception of type "InvalidArgumentException"
Clicking on the notification tray icon also says "There are no notifications", however I did get the email about a notification, and I see the correct number of notifications on the tray icon.
The "Alerts" feature is working as expected.