I'm using League\Csv to reformat CSVs. I'm reading in a CSV, manipulating the data, then writing the result out to a new CSV.
Reading the docs it says when reading a CSV it will
Filter out the empty lines;
Is there any way to stop this from happening?
Have you tried using a Statement object to process the Reader? It gives you more control over the selected rows. Perhaps the default statement would not include empty row filtering.
https://csv.thephpleague.com/9.0/reader/
See Records Selection, Advanced Usage.