Problem with referencing a specific dataset column

Hi Folks
I am having a problem with referencing a specific column in a dataset.
My schema uses the dataset type to pull a random value from this column (example… a random product reference), if i select another column (e.g. ProductName) it works fine, but this specific column just shows as empty. I have tried to reload a new dataset from a csv in case there was some sort of formatting issue but I cannot work out why this is not working.
The problematic column is a product reference for example : PRD0050001, PRD0050002, PRD0050003
Can anyone help ?.
Cheers