Show/Hide captions options no appearing when using Zoom Meeting SDK

Question

We are using Meeting SDK (Javascript, client view) to load a webinar on our website. The problem is that our webinar is supposed to incorporate captions. Even though the Show/Hide Captions appears at the bottom, when the user clicks on the arrow to see options, nothing happens. We have run the same webinar in the Zoom app and a menu pops up when clicking the arrow. How can we get this to work with Meeting SDK ?

This is the client-view JS script provided by the SDK

ZoomMtg.setZoomJSLib('https://source.zoom.us/2.13.0/lib', '/av')

ZoomMtg.preLoadWasm()
ZoomMtg.prepareWebSDK()
// loads language files, also passes any error messages to the ui
ZoomMtg.i18n.load('en-US')
ZoomMtg.i18n.reload('en-US')


var authEndpoint = 'https://ourendpoint.com'
var sdkKey = 'lskjasldjlajd'
var meetingNumber = '1234567890'
var passWord = '12345'
var role = 0
var userName = ''
var userEmail = ''
var registrantToken = ''
var zakToken = ''
var leaveUrl = 'https://zoom.us'

function getSignature() {
    userName = document.querySelector('input#attendeeName').value
    userEmail = document.querySelector('input#attendeeEmail').value

    fetch(authEndpoint, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json'
        },
        body: JSON.stringify({
             meetingNumber: meetingNumber,
             role: role
        })
  }).then((response) => {
    return response.json()
  }).then((data) => {
    console.log(data)
    startMeeting(data.signature)
  }).catch((error) => {
    console.log(error)
  })
}

function startMeeting(signature) {

  document.getElementById('zmmtg-root').style.display = 'block'

  ZoomMtg.init({
    leaveUrl: leaveUrl,
    success: (success) => {
      console.log(success)
      ZoomMtg.join({
        signature: signature,
        sdkKey: sdkKey,
        meetingNumber: meetingNumber,
        passWord: passWord,
        userName: userName,
        userEmail: userEmail,
        tk: registrantToken,
        zak: zakToken,
        success: (success) => {
          console.log(success)
        },
        error: (error) => {
          console.log(error)
        },
      })
    },
    error: (error) => {
      console.log(error)
    }
  })
}