The problem arises because of the different word order brought about by substituting a person's name by a personal pronoun.

Tu rappelles Audrey Hepburn à Sean. -- You remind Sean of Audrey Hepburn.

Tu lui rappelles Audrey Hepburn. -- You remind him of Audrey Hepburn.

Note that à Sean gets replaced by lui and changes place.

I find the explanation very confusing e.g. "You remind him of Auidrey Hepburn" is "Tu lui rappelles Audrey Hepburn" but "She reminds her sister of Alain" is "Elle rappelle sa soeur a Alain".

Why is the latter sentence not " Elle sa soeur rappelle Alain"?