There is a built-in limit of about 4 GB for generating ISO files with xorriso, which pyfll is using to generate the Siduction ISOs. If I understand it correctly it has something to do with the RockRidge extension. Be that as it may 🙂, I crossed that limit when generating my personal KDE-Siduction ISOs. As I do not have that many differences to the standard ISO, you may cross this limit too, soon.
There is a rather simple way out of that, which works for me. So I am posting it here to make things easier for others.
[It also fixes a typo(?) I mentioned in another thread.]