Hi,
Using the latest version 1.44.1 of NanoPlot, installed with Conda, I get a perfect HTML output of the Ploty graphs but the PNG files are blank, meaning that they are without any data. No dots shown on the LengthvsQualityScatterPlot_kde.png and only a N50 line in the other plots.
My command looks like this:

❯ NanoPlot --verbose --outdir "./test" \ --N50 --maxlength 2000 --color black --colormap Greys \ --plot kde -t "8" --format png \ --fastq ./*.fastq.gz

There are no error messages from NanoPlot.
May it be that there was a change in some supporting software?

Cheers,
Stephan