As a Scrum Master, here are two valuable actions you can take to address the situation where the Product Owner is not collaborating with the Development Team during the Sprint:
Facilitate Communication: As a Scrum Master, you can facilitate communication between the Product Owner and the Development Team. You can encourage the Product Owner to be more involved in the Sprint and collaborate with the team to ensure that they are aligned with the project goals and priorities. You can also help the team to better understand the Product Owner's expectations and requirements by organizing meetings or workshops where they can discuss the requirements and ask questions.
Coaching and Training: If the lack of collaboration is due to a lack of understanding of the Scrum framework or the Product Owner's role, you can provide coaching and training to both the Product Owner and the Development Team. This will help them to better understand their roles and responsibilities and enable them to work more effectively together. You can also provide guidance on how to use Scrum artifacts and tools, such as the product backlog, sprint backlog, and daily scrum meetings, to improve communication and collaboration between the team and the Product Owner.