Iphone duo not paired with usb c apple pencil

This is a known is with a limited subset of iPhone Duo owners. Apple Support has acknowledged the bug and is reportedly working on a fix that will be released in a future update.

You’re welcome to provide additional feedback via Apple’s official channel. Your comments will not be reviewed by Apple. Apple will make changes based partially on the feedback they receive through their official channel, linked below .

Product Feedback - Apple

Hi there

Please try this

To pair the USB-C Apple Pencil with the iPhone Duo (requires iOS 27.2 or later)

1. Make sure your iPhone Duo is updated to iOS 27.2 or a later version.
2. Slide open the back cap of the Apple Pencil to expose the USB-C port. 
3. Connect a USB-C cable from your iPhone Duo to the USB-C Apple Pencil. 
4. When the pairing prompt appears on the screen, tap Tap to Connect. 

My USB Apple Pencil would not pair with my iPhone Duo. The pencil and the phone were charged, the USB cable worked, the same Pencil would pair with an iPad, and the USB port worked fine on the phone for other things. I tried all kinds of things to get it to pair.

What finally worked was plugging the USB cable in while the iPhone Duo was shut. Then it paired straight away, no issues. Now it works fine whether the phone is open or shut.