If I remember it right, NAND problems were related to a weird original configuration where it was divided into two parts. First part was used "as is", but the second used eec or some kind of scrambling. First part had U-boot and maybe uImage while second part had everythin else.
This structure was not easy to be used by third part developers.
I have myself a configuration where U-boot and U-boot environment still stands on NAND, but everything else is on SATA disk. U-boot version is 2019.04 because I did not manage to make any more resent version work. Advantage of this conf is that I can boot it without SD card.