Cant see webcam video of host - screen works

Description
I created a small App that allows our customers to join meetings easily. Now when they join the meeting on the website, they cant see anything. Only when the host of the video shares his screen, they see the screen. But they should also be able to see the video of the host from the beginning. It is very customized, because the user should not be able to click or do something.
Below is my js and my css. The secret function is written in php and works fine.

Error
/

Which App Type (OAuth / Chatbot / JWT / Webhook)?
JWT

$(".playvideo").on("click", function () {

    ZoomMtg.setZoomJSLib('https://dmogdx0jrul3u.cloudfront.net/1.7.7/lib', '/av'); 
    ZoomMtg.preLoadWasm();
    ZoomMtg.prepareJssdk();
    let meetingid = parseInt(this.id);
    var arr = {"meetingid": parseInt(this.id)};

    $.ajax({
        url: "url",
        type: "POST",
        data: arr,
        success: function (result) {
            let data = JSON.parse(result);
            console.log(data);
            ZoomMtg.init({
                leaveUrl: 'url',
                showMeetingHeader: false, //option
                disableInvite: true, //optional
                disableCallOut: true, //optional
                disableRecord: true, //optional
                disableJoinAudio: false, //optional
                audioPanelAlwaysOpen: false, //optional
                showPureSharingContent: false, //optional
                isSupportAV: true, //optional,
                isSupportChat: false, //optional,
                isSupportQA: false, //optional,
                isSupportCC: false, //optional,
                screenShare: false, //optional,
                rwcBackup: '', //optional,
                videoDrag: false, //optional,
                sharingMode: 'fit', //optional,
                videoHeader: false, //optional,
                isLockBottom: false, // optional,
                isSupportNonverbal: false, // optional,
                isShowJoiningErrorDialog: true, // optional,
            });
            
            ZoomMtg.join({
                meetingNumber: meetingid,
                userName: 'User name',
                userEmail: 'kristof.heck@gmx.de',
                passWord: data.passwort,
                apiKey: data.apikey,
                signature: data.secret,
                participantId: 'UUID',
                success: function(res){
                    console.log(res);
                },
                error: function(res){console.log(res)}
            });
        },
        error: function (error) {
            console.log(error);
        }
    })
});

var buttonFound=false;
var t = setInterval(function()
{
    var startButton = document.getElementById("pc-join");
    if(startButton!=null){ 
        buttonFound = true;
        startButton.click();
    }
    var startButton = document.getElementById("pc-join");
    if(startButton==null && buttonFound){
        clearInterval(t);
    }
},500);


#zmmtg-root, .meeting-client, .meeting-client-inner {
width: 100%!important;
height: auto!important;
position: relative!important;

}

#wc-footer {
bottom: auto !important;
width: 100% !important;
}

#dialog-join {
width: 100% !important;
}

#sv-active-video, .active-main, #sv-active-speaker-view, .main-layout {
height: auto !important;
width: 100% !important;
}

.suspension-window {
transform: translate(-444px, 10px) !important;
}

#dialog-invite {
display: none;
}

#dialog-join {
display: none;
}

.meeting-app {
width: 100%!important;
height: auto!important;
}

.viewport {
width: 100%!important;
height: 396px!important;
position: relative!important;
display: block!important;
float: none!important;
left: 0!important;
margin-left: 0px!important;
margin-top: 0px!important;
}

canvas {
width: 100%!important;
min-width: 100%!important;
min-height: 100%!important;
height: 100%!important;
position: absolute!important;
}

screenshot left when joining the meeting, screenshot right only after host shares his screen

No one has a clue? - I tried it with a Webinar now, but still the same. The User cant see the webcam video of the host. Sharing Screen works fine.

Hey @kristof.heck,

Can you see the host if you do not modify any of the CSS and just use the Zoom Web SDK CSS?

Thanks,
Tommy