Just a guess, but I think Windows & Bitlocker knows your SSD is hardware self-encrypting. This means the SSD is always encrypting your data, but it is not secure because the encryption key has not been secured with a password. In Windows Explorer does it show the drive as encrypted or using Bitlocker? Try right-clicking on the C: drive for options. In Settings, see if there is an option to enable or activate Bitlocker. This should start the process to secure the SSD's encryption key.
If this is what is happening, I personally think it is a poor way of Windows displaying Bitlocker status as it can give peope a false sense of security.
I don't have much experience with Windows 10 or Bitlocker so take this with a grain of salt.