After some comparisons with other examples, and experimentation (and noticing this sample works fine when plugged in to a USB 2.0 host port) I've managed to "fix" the problem by changing the declaration in CyFxUSBDeviceDscrSS to be USB 3.0 rather than USB 3.1. I would still appreciate advice on this -- why would the sample be declared as a USB 3.1 sample and why would this then cause the debug endpoint not to function? Is this an error in the sample code?
We see that you have created a technical support case with the same issue. We will continue this discussion in the case .
This looks like an issue with the cyusb.dll library. W are checking this internally and trying to fix this. Until then as a temporary workaround, please specify it as USB 3.0