How to reference assigned value from dropdown field

How to reference assigned value from dropdown field

According to to this knowledge base article it should be possible to reference the assigned value of a dropdown field: https://help.zoho.com/portal/en/kb/forms/how-tos/form-building/articles/how-to-use-the-values-assigned-to-choices-in-formulas-email-notifications-thank-you-page-and-integrations

I'm trying to reference the assigned value of a dropdown field from a description field using a token like ${zf:Dropdown.Text} but it doesn't work. Referencing the display value using ${zf:Dropdown.Text} does work as expected. There's also no option for inserting the value from the field label menu (see attached screenshot).

See this simple repro for an example: https://forms.zohopublic.eu/canford/form/DropdownValueTest/formperma/84_43XHYSYR1pYTc_DPtVtDS1ZN5ZBsNDgtlFBH2Sbk

Is there some way to make this work?

Thanks,
Pete.