Notifications panel is always empty on `develop.element.io`

[MadLittleMods]

Steps to reproduce

1. Open the notification panel (accessed via the bell icon in the top-right)
2. Notice how the notification panel doesn't have any notifications listed

You're all caught up

You have no visible notifications.

This is only broken on develop.element.io

app.element.io (working ✅)	develop.element.io (not working ❌)

Outcome

What did you expect?

Notifications to be shown

What happened instead?

Just shows an empty placeholder view

When opening the panel, the following is logged to the console,

can't initialise scroll state because messagePanel didn't load

Operating system

Windows 10

Browser information

Chrome Version 107.0.5304.88

URL for webapp

develop.element.io

Application version

Element version: e21eb25-react-a347525781e1-js-4a33e584b01d Olm version: 3.2.12

Homeserver

matrix.org

Will you send logs?

Yes, see https://github.com/matrix-org/element-web-rageshakes/issues/16781

[weeman1337]

Could this be related to threads?

[t3chguy]

staging.element.io needs testing as this could be a release blocker

Does not affect staging

[t3chguy]

Regressed by matrix-org/matrix-js-sdk#2835