Hi Jun,
A colleague of mine that is working with me on this project already tested this example using the C# application when the project started. My colleague deployed the example to the lpcxpresso55s36 board and she got the same behavior regarding communication. That example works fine with the C# application, but that example doesn't involve the problem that I am reporting here.
I deployed a faster test that uses the onboard led. I added a code line so the led turns on when the board is plugged into the computer. Then I added a few code lines to turn the led off, where I understood that the device should recognize that was umounted. However, the led keeps turned on beside it was umounted.
Let me clarify that the device recognize that it was connected to the host and communication flow works fine. The problem is only when the device is unplugged. It desn't recognize the umount action.
In addition, to put you in context, we aren't hobbists. Our company name is Focus, and we are working on this project to a customer in the USA. Therefore, it is important to us to solve this issue.
Finally, could you check using also the onboard led if the board detects when it is umounted???
Keep in touch!
Martin