First I have to say: thanks a lot for the fast reply and support
I did as you asked and the tool shows:
Identification Optiarc DVD RW AD-5200S
Vendor specific info Nov05,2008 BT-LIGGY
Region Control RPC1
So this should confirm I did flash the right firmware.
I have no clue whatsoever which "something" on my PC might prevent bitsetting commands to be forwarded to the drive, I kinda doubt that is the case.
Could it be that maybe you did do something wrong patching in this specific case? I would really like to have the bitsetting capability for this drive.