Please check if you have set colour mode correctly…
OK you say you set the colour mode correctly to B&W when converting. However, looking at the histogram in Lightroom that you show, there is evidence of some colour. The place to look for any other trouble first and foremost is in NLP’s edit tab itself, not the stuff from the Lightroom tone controls you posted - those are irrelevant. Make sure in the NLP Edit tab that Temp and Tint are neutral. Click the White Balance tool on a mid-grey tone in the converted photo. Then go to Lightroom and make sure you have Vibrance and Saturation set to 0 because those can introduce color bias. See whether those measures clear it up.



