Fetch dosen't work only mobile platform in hosted test

Extensions
5

I’ve debuged it below.

function FetchUpdate()
{
    $('#log').text('FetchUpdate()<br>');
    let lu = lastUpdate.toJSON();
    $('#log').text('lastUpdate : ' + lu + '<br>');

    fetch(serverURL + '/update', {
        method: 'POST',
        headers:
        {
            'Content-Type': 'application/json'
        },
        body: lu
    }).then(function (response)
    {
        $('#log').append('FETCH SUCESS');
    }).catch(function (err)
    {
        $('#log').append(err);
    });
}

It’s again log Failed to fetch.
so I changed method ‘GET’

fetch(serverURL + '/update', {
        method: 'GET'
    }).then(function (response)
    {
        $('#log').append('FETCH SUCESS');
    }).catch(function (err)
    {
        $('#log').append(err);
    });

but it’s the same err.

What am I missing? T_T
I’ve debuged video_overlay with chrome developer kit.
It’s show what I am missing from inspect network.
but in mobile, in twitch app, I cant check my packet…
I tried packet capture and show that but its incoding SSL.
I tried to decode it, I failed.
I need help… sorry…