Classic brush tool glitch?

I just switched to a new computer (Windows) and installed Animate. Now whenever I used the Classic Brush tool, each stroke starts out as slightly transparent with a lined pattern inside. This pattern disappears when I release my pen and the stroke returns to normal. This doesn’t interfere with the drawing, but it’s definitely annoying. The Fluid Brush or Pencil do not have the same issue.

Here is a video of what it looks like.

Is this an issue with Animate itself? Or does this indicate something else like a driver problem? I use a Cintiq 16.