Digitalization, with its potential to enhance the openness of client–contractor knowledge collaboration (KC) at the front end of complex engineering projects, is gaining traction among project scholars and practitioners. Despite this growing interest, project actors still struggle to bring client and contractor experts into an open, digitally enabled collaborative space where they can freely access and cocreate project-related knowledge. In this context, our case study explores client–contractor KC in the front-end phase of oil and gas projects in Norway to understand why project actors struggle to achieve KC openness in the digital age. Based on our qualitative analysis, we developed a model that displays two intertwined aspects giving rise to tensions between knowledge sharing and protection. First, we show that these tensions stem from fragmented awareness of the expertise in the collaborating project organization. Second, we highlight how intrainstitutional complexity, instantiated in coexisting conflicting logics of digital and collaborative action, underlies divergent beliefs and behavior toward client–contractor KC and its digitalization. We offer novel insights into the project management literature by showcasing how organizational heterogeneity, in terms of expertise and institutions, challenges project organizations' pursuit of open, digitally enabled client–contractor KC during the front-end project phase.