The project manager should hold a meeting with the client to address the issue of the challenged and delayed payments. This is because the payment issue is a potential risk that could affect the project performance, cash flow, and stakeholder satisfaction. The project manager should communicate with the client to understand the root cause of the problem, clarify the expectations and obligations of both parties, and negotiate a mutually acceptable solution. The project manager should also document the issue and the agreed actions, and monitor the progress of the resolution. The other options are not as effective or appropriate as holding a meeting with the client. Adding nonpayment to the issue log and keeping tracking payments is a passive and reactive approach that does not address the underlying problem or prevent it from recurring. Reviewing past projects for payment-related lessons learned is a good practice, but it may not be relevant or applicable to the current situation, and it does not involve the client's input or feedback. Conducting a meeting with the project team to update the procurement management plan is not necessary, as the payment issue is not related to the procurement process, and it may not reflect the client's perspective or agreement. References: PMBOK Guide,
6th edition, Chapter 10.3.2, 12.3.2, 13.3.2, How to Manage Project Payments - ProjectManager.com