Because there is so much discussion information from prior posts information can get lost or forgotten by those who are reading this. Just to clarify as I don’t see or may have missed you mentioning it. What is the specific firmware version of the old My Cloud drive before cloning it?
Digging through old discussions (and user Fox_exe’s directions) bring up this this post:
That person seems to have a similar problem where the My Cloud Dashboard formatting fails after they tried replacing their v2.x firmware single bay My Cloud hard drive. Not sure, after reading it several times, if I understand exactly how they fixed it. They seem to suggest, when using the Fox_exe directions, they had to format all but the swap partition (usually /dev/sdb1) to EXT4 before pushing the files as indicated by Fox’s unbrick method to the drive. Perhaps one suggestion is the following. After cloning the old drive to the new one, open the new drive using Linux or Gparted. Then use Gparted to expand the user data partition (usually /dev/sdb3) so it uses all the rest of the unused drive space and reformat the user data partition (usually /dev/sdb3) to EXT4. Then see if the My Cloud Dashboard can finish the formatting to JOBD if it asks to format the drive.
Edit to add: Another possible suggestion. After cloning the drive, upon first boot, bypass partitioning the drive if you can and instead go the the Dashboard > Settings and do a System Only Restore and see if that helps fix anything.