How to hide "Context Value" in Add a contingent worker>Assignment in VBS

Summary:

I'm not able to hide "Context Value" following the path in VBS: Add a contingent worker>Assignment. I don't see the buttons to eventually make the field Optional/ Required or Visible/Hidden.

For other actions (such as Hire an employee) using VBS I was perfectly able to hide it. How is that possible and how can I solve this issue?

Content (please ensure you mask any confidential information):

Valore Contesto (IT) = Context Value (EN)

Version (include the version you are using, if applicable):
REDWOOD