Unable to HTML5 Mute Video Tag in Firefox

I want to make a video call with webrtc. I have two streams, one is local and the second one is remote stream.

In Chrome, I mute my video tag in order not to hear my voice which leads to echo. My HTML tag is like;

<video style="position:absolute;right:5px;bottom:5px;display: inline;" class="localVideo" autoplay="autoplay" 
muted="true" 
src="mediastream:3ffffe01-da89-44d9-b9cf-454b11ec6a6a" height="25%" width="25%"></video>

In Firefox muted="true" property not working, so that I hear my own voice. I tried to set muted propery with many ways in other topics like;

var video = document.querySelector("#movie");     
video.muted = true;

different variations of this code snippet with jquery didn't worked.

Then I've decided to add controls property to the video tag, in order to watch how Firefox control buttons works. I've seen that mute button on Firefox controller doesn't works either.

Is this a known issue, if so is there any workaround to overcome this issue?

Thanks.