Can't openn NLP on already converted negatives

I recently scanned and imported 4 rolls to Lightroom. I converted them all with NLP, edited some of the pictures and left the rest unedited.

Now I’m trying to edit this pictures, but can’t seem to get NLP to open. It’s not working on any previous converted picture. On some pictures it comes up, but it thinks the image hasn’t been converted yet.

Some pictures are showing this error " There was an unknown error while writing metadata to this photo. Retry?" Don’t know if it’s related.

I’ve tried some steps from another question, resetting Lightroom settings, and importing a new negative. This steps work, but after a couple of tries it stops working. Don’t know what to do.