By design, the Active Roles Synchronization Service or Quick Connect will faithfully synchronize the attributes from a source object to a target object.
In some instances, the source data may contain a NULL value. This could possibly result in overwriting data in the target system.
If this behavior is undesired, it is necessary to use a script to skip over this value.
For two Active Directory systems, in order to avoid overwriting the displayName attribute in the target system with a NULL value from the source system, the following PowerShell script could be leveraged: