Notification dropdowns and checkboxes failing to save in Notification settings view

Description

Notification settings aren't saved.

Steps to Reproduce

1. Go to Account => Notifications
2. Set the dropdown selections (Organizer notifications, Send notification e-mails). Set the "Participation notifications" checkboxes. Set the "Notification settings" checkboxes.
3. Leave the Notification section
4. Go back to the Notification section
5. None of the changes were applied

Expected behaviour:

Settings should be saved.

Actual behaviour:

Settings aren't saved.

Reproduces how often:

everytime

Versions

5.0.0