The short answer is yes, DPOD can work with external storage (AWS or other).
Based on your question, it sounds like your customers are using physical servers (Cell Members). If so, there are a few additional hardware considerations to keep in mind, such as the server model, socket count, and NUMA node configuration.
Also, it is possible that this is simply a retention configuration issue.
I believe the best way forward is to open a support case. Please make sure to attach a must-gather from all cell servers (both manager and members).