Perhaps try loading all your raw files(lights, darks, flats, biases) into DSS and set it up for the QHY8 to allow it to do the lot, rather than using Neb to cal and DSS to stack. You may get a better result.
This is the way I did it when I had a QHY8. I used Neb2 for capture of all raw data and stacked in DSS with good results.
Or, invest in PixInsight, you wont regret it.
