When I "MOVE" an Issue to a new project, you never get a screen asking for required changes to fields of that issues subtask.
On the confirm page you get a warning:

Note: Sub-Tasks associated with this issue will lose data stored in fields not applicable in the target.

However, a Bulk Move operation works differently.
We get a step in the wizard to ask the user to change values of fields that require adjusting.

It would be nice if this was consistent.