Ringing Tone is not working with locked phone

#### Describe the bug
I expect the phone to ring with the dedicated ringtone at all times. Of course this works with the phone app but when I get a call with Element Android there is only the short notification sound instead of the ringing tone. This happens when the phone is locked.

#### To Reproduce
Steps to reproduce the behavior:
1. Cell-Phone not in use
2. Somebody makes a direct call from Element
3. I only get the notification sound once, just as if an e-mail had arrived

#### Expected behavior
When I get a direct phone or video call from Element I expect the same ringing tone I get when someone does a regular cell-phone call.

In other words, the ringtone sound file should be played in a loop.

#### Screenshots
Not applicable

#### Smartphone (please complete the following information):
- Device: Motorola moto g 5G
- OS: Android 10

#### Additional context
- Element Android 1.1.9 Playstore
- Homeserver: Synapse latest dpkg from matrix.org