SO if a new user joins the organisation and you do a group chat with the user the new user does not see the whiteboard app when he or she clicks on share icon. But if the same users joins any TEAM meeting and then come back to group chat then he or she sees it. Any idea why the user does not see it the very first time when a group chat is initiated?
If I understand your issue, I think I know what is happening. Whiteboard is not available in the chat...only meetings, however, if you have a chat that is associated with a meeting, then whiteboard is available. In other words there are two types of chats. The standard IM type chat that is commonly used to send a coworker a quick message and the chats that are part of a meeting. Both will show up when you go to your chat tab inside of teams. The standard chats will have an icon that is the other persons icon (in a group chat all members of the group are in this icon) a meeting chat will have a calendar icon. The later will have whiteboard as an option.