1:1 calls going silent

### Steps to reproduce

On a 1:1 voice only call on Element, at around 7 minutes the call went silent for both sides and a missed call notification was received, although the original call was still ongoing. Ending the call and starting a new one fixed the behaviour, which happened again at around 8 minutes.

### Outcome

#### What did you expect?

I expected to have sound on the call for the entire call.

#### What happened instead?

Call sound cut off without warning.

### Operating system

macOS

### Application version

1.9.4

### How did you install the app?

App store

### Homeserver

vector.modular.im

### Will you send logs?

Yes

No source files, tests, or entry points are mentioned. Start by reproducing a 1:1 voice-only call on macOS with Element 1.9.4 and inspect the available logs; done means audio remains active for the call duration without a false missed-call notification.

Written by the indexing model from the issue text.