If your Facebook group chat is not working or suddenly it stopped working and your are checking Facebook group settings to find out the problem and enable Facebook Group Chat. Then you must know:

You cannot enable chatting in any Facebook group which has more than 250 members because Facebook group chat automatically gets disabled when the number of group members exceeds the default limit of 250.

There are only two conditions when Facebook Group Chat stops working:-

When your Group Chat Settings are Off

SOLUTION – Visit your group >> Select Edit settings >> Check Send Me Group chat messages

When Group members are more than 250

SOLUTION – You cannot do anything for this because members are more important than chat. Use Group Wall for discussions. You may tag your friends in a post by using @ followed by the name and it drops down the name suggestion. Select it and add friend for the public message. It sends a notification to the person you have added in your post.