Why do Intel Agilex® 7 devices exhibit Active Serial (ASx4) configuration failure?

Description

When using the Intel® Quartus® Prime Pro Edition Software version 20.4, you might see Active Serial (ASx4) configuration failure with Intel Agilex® devices when using an image compiled with AS_CLK=166 MHz. 
Affected devices are Intel Agilex FPGA AGFA014R24A and AGFB014R24A ES devices.

Resolution

To avoid this problem, use another AS_CLK frequency option. For example, 125 MHz, 100 MHz, and so on.