Lookup runtime function - using a list from another site

I'm trying to use the Lookup runtime function on Nintex 365 Forms to lookup a value in a list on a different site, but I'm having problems.

The documentation says:

lookup("list title", "column to filter on", "value to filter on", "output column")

List Title = To point to a list in another site, precede the list title with the server relative url path of the site, then delimit the list title with a pipe ‘|’ symbol, e.g. “/sites/siteCollection/siteA|customList”

On my form calculated field I have entered:

lookup("/squads/procurement|Person to Cost Centre","Title",Current User (Display Name),"Cost Centre")

There is an item in this list which matches my username.  However, when I preview the form it just displays: #Value!

Using IE Dev tools to troubleshoot, the error says:

errMessage = "List 'Person to Cost Centre' does not exist at site with URL 'https://<OurCompany>.sharepoint.com/essentials/Concierge'."

This site URL is the path to the site the form is on, so it seems to be ignoring the path I'm providing before the pipe character in the "list title" parameter of the formula.

Can anyone see what I'm doing wrong?

Many thanks for any help,

Ian