Why exact match doesn't work for Phone field in Matching Rule

Question

I have created a matching rule and a Duplicate Rule that should block a user from creating duplicates.

((Lead: FirstNameEXACTMatchBlank = FALSE) AND (Lead: LastNameEXACTMatchBlank = FALSE) AND (Lead: PhoneEXACTMatchBlank = FALSE))

But I am still able to create records with matching Phone numbers. Any help would be really appreciated.