Is the malfunctioning phone one of the older ones or a fairly recent one? I remember having issues with
MDE when my older phone was underpowered. In fact there were some times the phone told me to downgrade back to a previous version of MDE because it couldn’t handle the most current version. Perhaps there is a bug specific to certain models, like the issues the new M4 iPads are having with iPADOS 18.
If both phones are the same model, I would start by contacting Disney’s IT to see if they have a solution.