Ownership bias is a type of decision making bias that leads to an individual's tendency to prefer their own ideas over the ideas of others during the design process. While prior work has identified the existence of this effect in design professionals, this prior research failed to take into account the social effects of working in a team environment or to identifying the underlying impact of the characteristics of the idea set that impact the effects. Therefore, the purpose of this study was to identify the existence of ownership bias and the factors underlying its existence through two design workshops with 45 design professionals from two engineering companies. Through the study, design professionals individually generated and selected ideas as part of a 2-hour team design challenge. The ideas were rated for their perceived future value through team consensus and for their creativity by expert ratings. The results suggest that design professionals only exhibited ownership bias for ideas that were assessed to have little to no future value in the design process by their team members (low in idea goodness) and the creativity of the ideas did not effect this relationship. However, professionals did show a preference for ideas with high usefulness and low uniqueness, demonstrating a potential bias against creative concepts regardless of ownership.