When calling QualitativeSequence.GetSubSequence(), the new QualitativeSequence object being returned does not retain the original information stored in the properties ID and metadata.
For example:
QualitativeSequence qseq = new QualitativeSequence(Alphabets.DNA, FastQFormatType.Sanger, "ATGC", "ABCA");
qseq.ID = "my fastq sequence";
var newqseq = qseq.GetSubSequence(0, 2);
Console.WriteLine(newqseq.ID); // empty