Why do I see the problem "Internal loopback button" grey out after enabling it when using internal loopback in the Quartus® Prime Pro Edition Software version 21.3?

Description

Due to a problem in the Quartus® Prime Pro Edition Software version 21.3, you will see the problem "Internal loopback button" grey out when using internal loopback in the system console. 

Resolution

This problem is fixed beginning with the Quartus® Prime Pro Edition Software version 22.4.