Jira will allow you to use 'Bulk Edit' feature to change the issue type without regard for the different workflow that may be tied to that issue type. And if that different workflow has other states (i.e. does not contain the state that the issue is currently in), you could end up with an "orphaned issue". That is, the issue is left in a state that does not correspond to its current workflow and hence no transitions can be performed. Once this occurs, it cannot be fixed with bulk edit, transition or move. It can only be cloned and then deleted.

This is not an issue if the workflow scheme maps the same workflow are all issue types (e.g. they fall under the 'all unmapped issue types" setting) or if the same states exist in the different workflows. However, Jira does not check for this. It should either disallow the change of issue type during bulk edit operations, or it should issue a warning to the user.