Can't opt-out of notifications

Environment

• OS version: Windows 10
• Browser version: reproduced on latest versions on Chrome, FF and Opera, did not try other browsers
• Extension version: UI release 2020-1
• Last working version: ABP 3.10.2

Steps to reproduce

1. Install the latest ABP 2020-1 release (I used the build from https://gitlab.com/eyeo/adblockplus/abpui/adblockplusui/-/pipelines/278255560)
2. Open settings page, navigate to the Advanced tab
3. Try to uncheck the 'Show useful notifications' checkbox

Observed behavior

Checkbox remains checked.

Expected behavior

User should be able to check/uncheck the checkbox.

Further information

There were some changes to notifications in this Core ticket: https://gitlab.com/eyeo/adblockplus/adblockpluscore/-/issues/279 (but I don't know if they are related to the issue)

This regression was introduced in eyeo/adblockplus/adblockpluschrome#276 (closed).