Missing button in FaceTime to request remote control

As an IT support provider for family and friends, I was excited about the new feature in iOS 18 that allows remote control of another person's iPhone during a FaceTime call. However, although I can view their screen remotely, I cannot request control as the button for this function, that should be located at the bottom right of my screen (see attached image), is missing on my iPhone.

Anybody knows why? Could it be related to my status as an EU resident, given that certain iOS functionalities are apparently restricted within the EU?

?