Some sources suggest that Hepburn might have been less than thrilled with Taylor's initially unprofessional behavior on set, but there is no evidence of any major clashes. It's more likely that their contrasting personalities and approaches to acting simply led to some occasional tension rather than a full-blown feud.
Ultimately, the relationship between Hepburn and Taylor on "Suddenly, Last Summer" remains a matter of speculation. There's no concrete evidence of a significant problem between them, and they both spoke respectfully of each other in later years.