Attempting to update notification email for sub-group shows 404 page

Summary

Updating the notification email address used for a sub-group throws a 404. Doing the same thing for a root level group works as expected.

Steps to reproduce

1. Visit https://gitlab.com/profile/notifications
2. Update the notification email for a root level group, it works
3. Attempt to update notification email for a sub-group, you will get a generic 404

What is the current bug behaviour?

Throwing a 404 when attempting to update a sub-group notification email address

What is the expected correct behaviour?

Not to see a 404 and have that groups notification email updated

Relevant logs and/or screenshots

A (mostly) useless(?) video

simplescreenrecorder-2020-09-11_09.45.18