Mark as read button doesn't work on few channels

### Steps to reproduce

1. Open Element X.
2. See channels with unread messages.
3. Press and hold a channel name. Click 'Mark as read'.

### Outcome

#### What did you expect?
Channel gets marked as read.

#### What happened instead?
Channel doesn't get marked as read. Green symbol stays. Happens with 3 of my channels right now.
Also, sync issue is seen as messages in that channel are from over a week ago in Element X. This might be root cause but issue is different.
Web Browser Element confirms there's even messages today.

The issue persists over app restarts. It is still unread.
Oddly, on each app start, it is among top 5 listed channels for 10 seconds after which it says 'Syncing' and moves to nearly the end.
Also, surprisingly only 3 channels have this issue. This and most channels seem fine.

### Your phone model

Asus ROG Phone 7 Ultimate

### Operating system version

Android 15

### Application version and app store

Element X version 25.06.2

### Homeserver

chat.mozilla.org

### Will you send logs?

Yes

### Are you willing to provide a PR?

Yes(once I am used to this codebase)