I just found an issue with the calligraphy tool. I've updated to 0.48. Whatever preset I use, whatever settings I use for the tool, it does not work. It sort of "flickers" a stroke erratically as I click and drag (or use my tablet pen,) but the stroke disappears. There's nothing for me to click on or modify either. I've tried setting the tool to have a stroke, to having a stroke and a fill, to just having a fill, no go. And no, I'm not drawing a white stroke on white paper The stroke is set to be a scarlet red.

Am I using it wrong? Is this a bug and if so, is there a fix?

it was a bug in 0.48.0, was one of the reasons we did 0.48.1 I believe. Should be fixed if you update to the point release.