I have one of these with NetApp firmware and got it to format to standard 4k a couple years ago when Chia was popular - I do know there is something special with the 528 vs 520, and mine was 520 when I got it.
The trick was to use the bootable SeaChest tools that Seagate has on their site - I couldn’t get it to work with anything else ( like sg_format ) either. It doesn’t work in Windows, for safety reasons I guess - so the USB builder with whatever bootable Linux image they use is the quickest and easiest way to get to it.
seagate /support/software/seachest/
If I recall correctly there was also some other hoop that I had to jump through, like doing an encryption key change security erase ( the quick one ) to mark the drive as completely blank before it would let me use fast format to change the sector size.
