I changed my csc back and forth to my normal one and checked for software updates eventually I got the update on my default CSC like everyone else, I just changed my csc to my default one until I got updates, it took me a few tries tho

I've changed my CSC multiple times, no issue, you must've done something wrong

it doesn't if u do it correctly, I did it using samfw and installing the proper USB drivers

it's probably a region issue like we are having in South Africa, change ur CSC to a region that got the update like Egypt then after u download the update change it back to ur default region

 logic doesn't make sense but u got the spirit 