I have been using NLP with Lightroom Classic for a while and love it. Today, I was editing a DSLR captured film negative and all was well. I decided to redo changes to one photo so I hit the reset button and the image reverted to a negative. When I tried to activate NLP with ctrl N, nothing happened. I rebooted my computer and still no luck. I have verified that the plugin shortcut is in Lightroom.
Dennis
Hey! Just ran into the same issue and figured it out. I had to revert to version 10.4 of Lightroom Classic for it to work and had to re-enter my license key after reverting. You can downgrade your version in the Adobe Cloud app, just click the three dots to the right ofLightroom Classic and select ‘other versions’.
I can’t execute your download in the Creative Cloud. No three dots appear to the right of Lightroom Classic in Creative Cloud. I am running version 11.1 and cannot activate NLP.
I actually tried to uninstall and reinstall NLP 3 times, and on the third try it worked. I also rebooted multiple times. I believe that there was a corrupted code stored in my computer and it finally was purged. I am back to normal now. Thanks for the comment.
Hi there, did you find a solution for this? I’m having a similar problem! Thanks 
I uninstalled NLP, shut down my IMac about 2-3 times (because it did not work on the first try) and reinstalled NLP and it has been working well since. I am not sure what the problem was in the first place, and I am not exactly sure if what I did actually worked. Regardless, everything seems to be ok now.
Yes I did, using the suggestions of 1) returning to Lightroom Classic 10.4 (which I was able to ferret out on the Adobe Creative Cloud website) and 2) reinstalling NLP. I am finding out, however, that it is easier and faster to do mass conversions of PrintFile negative contact sheets by scanning using SilverFast and my Epson V850 and then using Photoshop to do an inversion. That leaves color correction on selected negatives for another day.