No communication with FreeRTOS-Plus-TCP over the FreeRTOS Windows Port

Are you using Windows system calls for this? Also, as Richard asked, how are you doing IO for CLI?

You can break the code in debugger and examine the list there.

It turned out that I cannot use PREEMPTION in the Windows port. I changed configUSE_PREEMPTION to 0. It worked fine.

I do not think that assumption is true - the official windows port does support preemption. Unless it is because of some limitation in your application, I think it should work.