Can't add hourly rate to invoice

Hi, in the help window, I got the reply:

“To show the hourly rate, simply click on the relevant field and edit it. You can also add custom fields for additional information if needed.”

Neither of those seem to be possible for me, I’ve clicked everywhere and there’s no such options. I can add/change many other parts of the invoice, but I can’t add the hourly rate. Is that a paid feature only?

Also note that the hourly rate isn’t shown on your examples either – neither the sample image, nor the walkthrough video found on this page about how to create/edit invoices, Creating Invoices in Toggl Track | Toggl Track Knowledge Base

This is an essential component of an invoice. Please advise!
Thanks