All of the reference definitions are uploaded but I can not assign them to a worksheet.
After some trial and error I figured out that you need to add reference definitions via suppliers and they will be available to add them as a control reference or blank reference.
Step 1 Head to setup/suppliers/ and choose supplier and click add
Step 2 Complete the form fields and save
Step 3 Head to reference samples to confirm that the reference definition has been added
Reference sample is now available in worksheets