Hi Joseph,
Thanks for the update.
We would like to inform that the online demo sample will support more than one field because it is Multiselect template with Default mode, but your reported case is Multiselect with CheckBox mode. It will not support more than one field. As per our previous update, this is control’s intended behavior for CheckBox mode.
Please get back us, if you need further assistance.
Regards,
Ponmani M