Can't video or audio call in Zoho Mail group chats

Can't video or audio call in Zoho Mail group chats

Hello,
For some reason, we can't place audio or video calls in our group chats in Zoho Mail. The one to one chats have the video and audio call buttons and work perfectly fine. The group chats, however, do not have the audio and video button, and so we can't audio or video call. :( 
Here's a screenshot. The chat on the left is a one to one chat, while the one on the right is a group chat.


I am pretty sure I tested this once before with a group chat, and they did have the button. What's going on? Please help!
Thanks!
Noble Obodum
Webmaster, Adventist Outreach Kids
admin@theaoks.gq
info@theaoks.gq