Mentions in encrypted rooms don't highlight or make sound

### Steps to reproduce

Despite having broken both of my actual accounts in the same way, I can't reproduce this now on a test account:

1. Switch "Messages containing my display name" from Noisy to Off
2. Test it out for a bit, and realize that this breaks mentions
3. Switch it back to Noisy

### Outcome

#### What did you expect?

To resume the default behavior of being highlighted and pinged on any mentions

#### What happened instead?

I now receive highlights and pings on mentions in unencrypted rooms, but not in encrypted rooms.

For reference, here are my notification settings:


### Operating system

NixOS unstable

### Browser information

Firefox 99.0.1

### URL for webapp

develop.element.io

### Application version

Element version: 850a250cea91-react-3e31fdb6a71f-js-d190cdc307f1 Olm version: 3.2.8

### Homeserver

Synapse 1.57.0

### Will you send logs?

No

Start by reproducing the notification-setting transition in an encrypted room and compare mention behavior with an unencrypted room. Done means restoring “Messages containing my display name” to Noisy makes mentions highlight and play a sound in encrypted rooms as well.

Written by the indexing model from the issue text.