SEN0539 Offline Voice Recognition Module - No Serial output

Hi

I am having problems with the offline voice recognition module connected to Arduino via the DFRobot IO expansion Shield V7.1

Using the example code from the GitHub or  the code from the wiki page - the code compiles & uploads fine but i get no output on the serial monitor! Also the demo code from the wiki the light does not turn on or off

Running the normal “Blink” sketch the LED works fine

I get audio response to my voice commands ok so i know the board is working

I have tried both Arduino IDE V 2.2.1 & V 1.8 = same result

I have tried different models of Arduino UNO - same result

I have tried a simple serial.print test - works OK

I have tried 

I am running on Linux Ubuntu 20.04

Any help / advice would be much appreciated