iPhone mirroring problem with new 2024 M4 Macbook Pro

I've just received my new M4 Macbook Pro and I launched the iPhone Mirroring app, but it won't go beyond the set-up page. My iPhone is an SE running iOS 18.1.1.

Both devices are logged into the same iCloud account, wifi and bluetooth are enabled on both devices, and when I have Bluetooth settings open on the MBP, my iPhone sees the MBP, but the MBP won't see the iPhone.

I know that bluetooth is working on the MBP because it connects to my wireless headphones.

I have tried restarting both devices.

Any ideas? Thanks