Transferred images from iPhone through MyCloud are mostly gray on drive

That really pisses me off too. I’ve lost dozens of irreplaceable family pics because of that same issue. Usually it when I’m making a fresh backup of my data after support has no clue what the problem is so they say “We nedd to restore your device” There is always risk in compromising my data during this restore process and backups of high quality images are always degraded like that where theyre missing entire sections of the image. I’ve honestly never had this issue on any device other than WD. I usually compare the folder properties down to the exact number of bytes to ensure it looks like a complete copy but then notice images like that on my backups later on. Mine are usually giant blue squares tho.