STM32CubeMX V6.1.1 MDK 5.27 USB CDC fails for STM32L476RCT, OK for SMT32L152VCT

After spending a year or so on different processors, I returned to a new project using the STM32L476 which I had used STM32CubeMX V5.x on before.

Using STM32CubeMX V6.1.1 with MDK 5.27 even the simplest USB CDC serial port device would not work; the windows driver gets part way through initiating the device as a serial port and then fails to open with error code 10. The same settings using CubeMX V5.x did not have this problem.

Other notes:

Using STM32CubeMX V6.1.1 with MDK 5.27 with the same usb cdc configuration but on a STM32L152RC runs perfectly.

With STM32CubeMX V6.1.1 one can ONLY select firmware package STM32Cube FW_L4 V1.16.0, and editing the .ioc file to force an earlier package e.g. STM32Cube FW_L4 V1.13.0 fails to produce compile-able code.

The only GOOD thing is that finally there is a "CDC_TransmitCplt_FS" hook added which I always had to add manually before.

If anyone knows a work around please let me know, otherwise I will have to set up another machine (yet again) for running STM32CubeMX V5.x on.

Thanks.