In the iOS 11.3 Beta, there was a new feature added called USB Restricted Mode. This was the description for it: To improve security, for a locked iOS device to communicate with USB accessories you must connect an accessory via lightning connector to the device while unlocked – or enter your device passcode while connected – at least once a week.
I THINK it might have been removed in the final version of 11.3 but I'm not sure. Does anyone know if USB Restricted Mode is still a thing? If not in 11.3, is it currently in the 11.4 beta? I have been unable to find any information in any documentation.