Windows 10 does not recognize hardware encrypted bitlocker volume

I use Windows 10 Pro/Education on a self encrypting Samsung SSD Drive (Evo 850) and configured/installed it by following this guide [1]. I configured bitlocker to ask for a PIN before booting Windows and the lock symbol in the explorer as well as manage-bde -status command showed that bitlocker successfully encrypted system drive C: and really used hardware encryption of the Samsung drive.

Everything seemed to work fine, but after I updated most of the drivers for my Dell Inspron 15 7559 to the newest version [2] bitlocker first asked to enter the recovey key because configuration has changed and then the bitlocker symbol in Windows explorer was gone. After the boot Windows told me that the drive is not encrypted, if I tried to encrypt the drive only software encryption was offered.

However Windows stills aks me for the pin at bootup and the drive is not accessible through a live system, so it seems that the drive is still fully encrypted. If I start a command line before boot up (recovery options) manage-bde -status command still shows that the partition is hardware encrypted and managed by bitlocker. But after booting Windows fails to recognize the encryption, so I can't access the configuration for this encrypted drive for example to change the password or disable bitlocker.

Has anyone an idea how to make Windows recognize the encryption after bootup again?

Output of manage-bde -status C: after start-up in Windows installation:

Volume C: [Windows] [OS Volume]

Size:                 209.04 GB
BitLocker Version:    None
Conversion Status:    Fully Decrypted
Percentage Encrypted: 0.0%
Encryption Method:    None
Protection Status:    Protection Off
Lock Status:          Unlocked
Identification Field: None
Key Protectors:       None Found

Output of manage-bde -status C: before start-up using bitlocker recovery mode command line*:

Volume "C:" [volume is unknown]
[Data Volume] 
    Size:                 Unkwon GB
    BitLocker Version:    2.0
    Conversion Status:    Unkown
    Percentage Encrypted: Unkown %
    Encryption Method:    Hardware Encryption - 1.3.111.2.1619.0.1.2
    Protection Status:    Unkown
    Lock Status:          Locked
    Identification Field: Unkown
    Automatic Unlock:     Disabled
    Key Protectors:       
        Numerical Password
        TPM and PIN

*Note: Obviously I couldn't copy&paste the second output, I also had to translate it from German, so there might be some minor inaccuracies.

[1] https://helgeklein.com/blog/2015/01/how-to-enable-bitlocker-hardware-encryption-with-ssd/

[2] http://www.dell.com/support/home/us/en/19/product-support/product/inspiron-15-7559-laptop/drivers