I think this is related to the Windows language.
This error occurred on a computer with Turkish windows installed and on a virtual computer.
Where are the files for your tracks ?
You have to add the tracks individually for each "instance" of PlayIt Live (I've never tried copying a library).
I found making a folder structure reflecting the rotation rules you wish to use then adding those tracks folder by folder to PlayIt Live to make track groups named as needed seems the best way.