How can HR Access employment history of their former employees

Hello,

I did a test in our environement by transferring an employee from an entity X to an entity Y.

The HR of the entity X do not have acces anymore to the employee despite the fact that he made an advanced search chosing inactive asignment and an effective date prior to the date of the transfer to the entity Y.

Is there anything that should be modified in the security or the management of assignments so that we can give access to former employees?

Thanks and regards,