Screen extension not working - only mirroring

Using an Portable Monitor (ARZOPA 17.3 Inch) plugged into my iPad Pro 12.9 inch 5th Gen M1 and it only mirrors - no sign of the screen extension I have seen people show elsewhere. Is anyone else having problems?

If I use USB C then it only mirrors (and yes, I added a mouse and keyboard) - I don't even get an option to arrange different screens ("built in display" is not listed)

If I use a dongle (I have tried three) to HDMI there is no signal.

Any help much appreciated!