You can turn BitLocker Auto-unlock for fixed or removable Data Drives, on or off using BitLocker Manager, Command Prompt, and PowerShell. In this post, ...

I have a Server 2016 box with all drives encrypted, with a USB key inserted during boot so that it auto-unlocks itself. I have secondary drives that are also encrypted with the recovery file saved ...

Thankfully, auto-unlocking is the default behavior for drives that Windows encrypts automatically, so you shouldn't have to worry too much about this on the latest versions of Windows.

First try restarting your Windows computer and then try the encryption again and see if The data drive specified is not set to automatically unlock issue is resolved. If not, try the next solution ...