Missing term match with required field

Thank you so much for this project. It's very usefull.

I have some problem with required field.
This is my case:
- field references to taxonomy term
- this field use entity reference widget.
- in the permission table the user can't add terms to the taxonomy vocabulary.

when user compile insert form of the node, add some text to the field that is not match to any term in the vocabulary.
user can submit insert form without problem but in the saved node the field is emtpy.

Please help me.