Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
Next confirmation: ECC works on Gigabyte's X399 DESIGNARE EX board just fine.
I tested with 4x 16GB 2Rx8 modules (CT16G4WFD824A) and 8x 8GB HPE 2Rx8 unbuffered ECC modules.
In fact I was able to boot the machine with 4x 16GB + 4x 8GB resulting in 96GB ECC RAM :)
Linux 4.14 kernel boot messages...