If you experience this problem then you might have your parcel settings set to "No public Access".
Parcel access might not work as expected since the newest release. Make sure you are on the Access list if you have your parcel set to private. People will be able to get on your parcel but they will not be able to see the chat if they are not on the access list. Same might happen with bannlists.

If you do not wish any strangers visiting your region, please set the public access off in your Region/Estate settings.