"I am also experiencing problems with the tool".
"You can no longer see differences etc...".
Since when exactly? Which version of our tool? For the exact same scene? What did you change in between?
What scene are you watching? Movie, time code and screenshot would help.
What parameters are you using for the dynamic target nits? Again screenshot would help.
You say you are getting the same same "stats"/ dynamic target nits numbers no matter what you set for the "dynamic tuning ".
This can happen is the scene frames have a peak lower than your set "NO compression limit" or minimum target nits. In this case: target nits = peak nits. And that would be the normal behavior.
And no: the static target nits only use your "real display nits" as input. Nothing else. So everything normal there.
Having done a number of experiments, I don't think it's your tool. If I use min & max of 20 I do see a difference. I think the problem is I'm using Ghost in the Shell (dark movie) and the dynamic nits tuning just doesn't come into play on such a dark movie.
I will try some other movies before I post again.