Hi there,
my Inkscape 0.46 has a behaviour which seems to be unique: any calligraphic lines I trace disappear just after I release the mouse button.

I did not touch any settings.

I checked all the FAQ and tutorials I could and Google, it seems this problem is not very common.

Anyone has noticed a similar behaviour? Any idea?

Thank you very much.

only guess is that the style has managed to get set to either off or white or something.

You should b able to see it if you change your display mode to Outline.