This study investigates the impact of ChatGPT as a collaborative tool in the ideation phase of human-centered design processes, involving 208 students across 37 groups. Through analysing student reports and reflections, both with and without ChatGPT usage, the study explores its impact on creative processes and its educational value. Our findings indicate that ChatGPT contributes significantly to enhancing the overall quality of creative projects and aids in problem identification, offering students broader perspectives. However, its contribution to enhancing creativity, feasibility and effectiveness of solutions was found to be marginal. We highlight the challenges of integrating ChatGPT in group work, particularly regarding its influence on group dynamics and creativity. This study highlights the need for more structured guidance on effectively using ChatGPT, balanced with encouraging student-led experimentation with the tool. We contribute insights into the nuanced application of AI tools like ChatGPT in educational contexts, especially in facilitating collaborative design tasks.