Notification settings "mentions only" not working

**#### Describe the bug
A clear and concise description of what the bug is.**
The "Mention only" Notification setting isn't working. When this setting is selected, users do not get any visual or sound based notifications when another user mentions their name.

**#### To Reproduce
Steps to reproduce the behavior:**
User 1 > Select a chat room > Settings > Notifications > Select mention only
User 2 (test user) > Mention User 1

**#### Expected behavior
A clear and concise description of what you expected to happen.**
User 1 should get visual and sound notification for mentions when the Mentions only setting is selected

#### Screenshots
If applicable, add screenshots to help explain your problem.
Selecting mention only should trigger a sound and visual notification

#### Smartphone (please complete the following information):
- Device: Samsung Galaxy A20e
- OS: Android 10

#### Additional context
- App version and store [e.g. 1.0.0 - F-Droid]
- Homeserver: [e.g. matrix.org]

Add any other context about the problem here.