Example Steps to reproduce:

1. assign the Assign Issue permissions to all roles
2. Add the following into property the Workflow Step:

   jira.permission.assign.projectrole.1=10002
   jira.permission.assign.projectrole.2=10001
   

   or refer to screenshot Property.png

3. expected result will the user with roles Administrators(id=10002) and Developers(id=10001) will be able to see the Assign Issue button or Assignee field in that step. However, only user Administrator will be able to see the Assign button/Assignee field

This is NOT reproducible with multiple Groups:

1. assign the Assign Issue permissions to all groups
2. Add the property the Workflow Step:

   jira.permission.assign.group.1=jira-administrators
   jira.permission.assign.group.2=jira-developers
   

3. all users that has membership to jira-administrators or jira-developers will be able to see the Assign Button/Assignee field