Amazon AppStream 2.0 Fullscreen Mode Button Not Working on Embedded Streaming Session

I have an AppStream 2.0 streaming session which is embedded within my website. When pressing the 'Enter fullscreen mode' button nothing happens.

AppStream 2.0 fullscreen button

The closest solution I found was to enter the browser's full screen mode using F11, but then the remote machine's resolution needs to be set manually from the toolbar. Additionally, the toolbar isn't hidden - which means the streaming session doesn't cover the whole screen.

How can I solve this issue?