Facebook introduced direct messaging or chats within Facebook Groups last year. But now the company is taking out this feature. The chat function created within Facebook Groups will become unavailable starting August 22nd. The existing messages created there will become read-only. You can search for these threads within the Messenger app, but you will not be able to add anything else or anyone within these particular chat windows. Facebook says it's exploring new ways for group members to communicate in real-time. The shut-down, however, does not affect group messaging or group chats within the Messenger app.
Source: Facebook