Students as partners (SaP) has become an impactful practice in higher education as it enables students to take ownership of their learning and exercise agency. However, the implementation of SaP, particularly in Asia, has encountered many challenges, including concerns about a large power distance between students and teachers. Despite the emerging interests in exploring SaP in several Asian regions, there have been few studies about students' experiences of partnership throughout a project life cycle. This study explores students' experiences of SaP in three projects spanning two research-intensive universities in Hong Kong based on the Cultural-Historical Activity Theory (CHAT) and positioning theory. Data were collected from exit interviews with student partners, their reflective writings, and their responses to open-ended questions in a post-project survey. Our main contribution is the discovery of multiple contradictions between the project designs and students' enactment of partnership. Specifically, students' hesitation in assuming a partner's role was related to their disciplinary identity, the inquiry methods of the projects, and the pre-determined project specifications. In contrast, the cultural factors, which are largely framed as barriers in the literature, only affected the partnership development at the beginning of the project. Our study implies that future SaP projects need to ensure the alignment between project designs and a partner's role to facilitate equal and sustainable contributions from students and staff members.