Team working hours were agreed at project start, but later one member says those hours no longer work due to personal commitments. What should the project manager do?

The correct answer is to change the duration of iterations to deliver more value. When a team member's availability changes, adjusting iteration length can help maintain a sustainable pace and ensure deliverables are still met. This agile approach focuses on adapting to team capacity while continuing to deliver value. Validating iteration goals with the customer is a good practice, but it doesn't directly address the team member's personal commitments or the impact on work capacity. Inviting the customer to daily meetings is also a good practice for transparency but doesn't resolve the core issue of reduced team availability. Helping the team redefine the MVP might be necessary if the scope is too large for the available capacity, but adjusting iteration duration is a more immediate and flexible response to a change in working hours.