Getting nested data as prefix doesn't work

[AristideBH]

Hello, and firstly, thanks for your interface !

I have been using it for as simple page slug for now, and it is extremely helpful.
But I am now trying to setup a more complex data model, where each page can have a parent page.
I got this part working using relational fields.

I'm now trying to set the child slug prefixed with the parent slug if it is present.
I have set a condition to the fields, for when it has a parent page linked, the prefix should be {{parent.slug}}/.

The result of this is a slug missing the variable, like so /page-slug, instead of parent-slug/page-slug.

However, setting the prefix to simply {{parent}}/ does correctly output the parent ID.
In my case it is an UUID, and therefore the page slug results in parent-uuid/page-slug.

It is supposed to work like so ?
I feel it should as nested data is listed in the prefix field

Hope my request is clear ;) thanks in advance !