This add-on will remove all options for user to set themselves invisible.
- Download attachment & unzip it.
- Log in to your Admin CP and click on "Install Add-on" at bottom left corner.
- Upload the unzipped XML file.
Set the default for new users:
Admin CP -> Home -> Options -> User Registrations -> Default Registration Values -> Show online status
Update the preferences of existing users by running this query on your database:
Before:UPDATE xf_user SET visible = 1