This anwser gives some examples of Late Latin texts using ille, illa, illud in ways quite similar to the usage of definite articles in modern Romance languages. However, I know that in some varieties of modern Romance languages, such as Sardinian or some varieties of Catalan, definitive articles derive from Latin ipse, ipsa, ipsum.
So, my question is: have some instances of Late Latin texts using ipse, ipsa, ipsum as definite articles been found?