2012 Macbook Pro second SSD
The "hang" is most likely caused by the HP SSD being pre-formatted for Windows computers (NTFS) which macOS cannot read by default.  If you wipe the drive with a macOS compatible format, it will likely fix the issue.

Using Terminal, issue the following command:

$ diskutil eraseDisk HFS+ Untitled GPT /dev/diskX



HFS+ is the format of the new drive
Untitled is the name of the new drive
GPT is the partition scheme
/dev/diskX is the drive identifier (use diskutil list to obtain identifier)