I’ve read that some users are getting an L value of around 14. I recently switched to HD Matte Black and printed the 129 target using the QuadP800-HDK7\K7-SEL-UHD-ConeType2.quad curve (on Cone Type 2 paper of course) and my black L value is 16.6. In addition, after profiling, this curve was not linear for me (I assume it should be linear as it matched the printer, paper and ink set I am using). I’m not sure what I’m doing wrong.
there’s a good chance that you have not yet purged the HD MK ink line.
Print 10 sheets of black ink with this method:
https://community.inkjetmall.com/t/how-to-flush-individual-channel-using-qtr-calibration-mode/2070