Do you want to save the stuff on hdd? might use ubuntu to access it if it sees it. Can use it to copy files off
Did you install win 10 on PC with hdd in PC? If so, ever booted ssd without it connected? Try that before the next step, just in case it doesn't boot.
You might want to try running http://www.dban.org/ on hdd (remove ssd before doing this, don't want to wipe ssd)
once hdd wiped pc might see it, not entirely sure why this happened but this might fix it.
I don't think the WD software can run on a hdd win 10 can't see - the WD reps normally look at storage posts so may jump in and confirm that or not