The following is taken from a warning notice issued by the American Printing House for the Blind:
The basic issue is that once you upgrade to 14.4, as soon as you lock your iPad or iPhone with the Mantis or Chameleon connected, the braille display will not automatically reconnect once you wake the device back up. You can force it to reconnect by leaving the terminal and reconnecting from there but then you won’t get braille. The only way to get braille back is to toggle Bluetooth on the iOS device but the issue will happen again as soon as you lock your device or it goes to sleep.
Another way that this issue can manifest is if you don’t lose your connection but use the braille display to wake up the iOS device, you can successfully wake it up and regain your connection but you will stop receiving braille. Regardless of how the issue appears, it is best to avoid it altogether by not upgrading to 14.4.