It looks like we're tracking a similar bug report about broken brightness controls on HP EliteBook 8560w in the 319 and later drivers in the NVIDIA internal bug tracker. That bug tracker is not visible to the public, but in case you want to check with NVIDIA support on the status of the bug, the bug number is 1372953.
The root cause of this issue has not yet been investigated, so there's nothing to report at the moment, other than that we are indeed able to reproduce this issue.
It looks like we're tracking a similar bug report about broken brightness controls on HP EliteBook 8560w in the 319 and later drivers in the NVIDIA internal bug tracker. That bug tracker is not visible to the public, but in case you want to check with NVIDIA support on the status of the bug, the bug number is 1372953.
The root cause of this issue has not yet been investigated, so there's nothing to report at the moment, other than that we are indeed able to reproduce this issue.