It is entirely normal to encounter problems attempting to clean install OS to your JetDrive 850, as the internet recovery will reinstall to your JetDrive the original operating system that came the same year with the Mac, and since the JetDrive 850 only works with High Sierra or later versions (10.13 or later), a clean install of an earlier MacOS is out of the question.
Our solution to this is as below.
1. Use Apple's original SSD as the internal start-up disk.
2. Power on and hold hown the "command" + "R" keys untill you see Apple's Logo.
3. In Disk Utility, format the Apple SSD to MacOS Extended (Journaled) & (GUID scheme).
* Please note that you have to change the view to "Show All Device" and GUID scheme is necessary for system install.
4. Return to Mac Utility and choose Re-install MACOS for a fresh installation.
5. Upgrade the MacOS to the latest version.
6. Connect an external HDD or SSD to your Mac, and format it to MacOS Extended (Journaled).
7. Use Time Machine to Backup the MacOS to the external drive.
8. Power off and replace the Apple SSD with the JetDrive 850.
9. Power on, hold down the "option" key, and select the external drive.
10. Format the JetDrive 850 to APFS (GUID scheme), and use Time Machine to restore the MacOS to the JerDrive 850.
11. Power off and disconnect the external drive.