Formative assessment is recognized as an important cyclical process for supporting student learning, but its implementation in higher professional education remains challenging. Difficulties may especially arise with complex competencies, such as epistemic agency, which are deeply embedded in professional contexts. This study therefore examined how teachers use formative assessment to foster epistemic agency and what obstacles they encounter. Six teacher teams from different higher education programs participated in group interviews, reflecting on their formative practices using the formative assessment cycle. The results show that while teachers are familiar with formative strategies, they struggle to grasp what epistemic agency entails, which affects the enactment of formative strategies across all phases of the cycle. The study highlights the need for professional development that integrates both the “how” and the “what” of formative assessment, and contributes to a better understanding of the pedagogical conditions under which epistemic agency can be meaningfully supported.