It should not be possible to set a note on a license term when no term value has been set. This works as described. However, when a user adds a note to a term without setting a term value, the user is still allowed to Update the license and receives no error, but the note is not saved.
In this situation, the user should instead be warned that they cannot set a note without setting a term value with the text "A value must be set for this term in order to save a note"
Create a license
Add a note to a license term without setting a value for the term
See no warning
Look at license terms - see that the note has not been saved