Why does my video call have only sound and no picture?

[MiaoMiaoai]

• Your Rocket.Chat app version: 3.5.1（258）
• Your Rocket.Chat server version: 2.1.0
• Device (or Simulator) you're running with: iPhone 7P ios13.1.3

I am in China
I display the video button in the demo
Who can help me?

[MiaoMiaoai]

[MiaoMiaoai]

Xcode console printing error：
[error][tid:com.facebook.react.JavaScript] undefined is not an object (evaluating 't.callUUID')
[fatal][tid:com.facebook.react.ExceptionsManagerQueue] Unhandled JS Exception: undefined is not an object (evaluating 't.callUUID')

[MiaoMiaoai]

I don't have this problem when I use other phones。
Talking to someone on video, I can't see the picture on my phone but they can。