Hey there, Jacob_8.
I'd recommend that you take a look at the boot priority in your BIOS/UEFI and see if the SSD has been selected as first booting device. Did you clone the OS to your SSD or was it a fresh install? If it was a fresh install did you remember to disconnect all other drives from the motherboard during the installation process?
As for troubleshooting, I'd suggest that you try the WD Black HDD with a different computer if possible, or at least with a different SATA port and cables on yours, to see if the same thing happens. I'd also recommend that you download DLG (Data Lifeguard Diagnostics), to see if recognizes the HDD and run both tests (Quick and Extended), to see if anything alarming pops-up. Here's how to do that...