When running example code which involves BLE on nRF52840-based boards, the devices (which have assigned names in the example code) don't show up on the iOS nRF Connect scanner. Other devices, such as laptops and Bluetooth headphones show up on the scanner, so it is working to some extent.
I uploaded the 'ble_blinky' example from nRF5 SDK onto the SparkFun Pro nRF52840 Mini. I know that nRF5 SDK is not recommended for new designs, however, there isn't good documentation around the use of nRF Connect SDK with the Sparkfun board.
I also tried using the Adafruit Feather nRF52840 Express, uploading the 'controller' example from the Adafruit Bluefruit nRF52 Libraries via the Arduino IDE (1.8.18, because there is a known issue with uploading to this Adafruit board using versions later than 2.0.0).
In both cases, the Serial output indicates the code is running.
Although I'm aware that I haven't used Nordic Semi's own DK, I feel like the above experience indicates an issue with the iOS app, not the hardware.
iOS nRF Connect: version 2.7.11
iPhone: iOS 16.1.1, iPhone 11