QCAD does not support all types of available XData (additional, typically non-standard data attached to objects). In most cases, you can simply ignore those messages.
If you are referring to those blue lines at various angles, these are polylines with a custom lineweight set to 0.23 drawing units. Since the whole drawing is about 7000 drawing units wide, 0.23 drawing units is indeed extremely thin (barely visible or not visible at all in a bitmap / on screen).
Perhaps adding a minimum line weight command line switch would serve you best? Can you confirm this?