Hi Todd,
I had a similar issue but going into my pen’s settings (Wacom software) I adjusted the sensitivity and soon had the pressure over reacting greatly (too sensitive!). Toning that down (and setting up separate pen settings for use with Animation Paper… as opposed to other programs… has pen pressure working nicely.
I still don’t have the settings entirely optimized as I still haven’t got lines smoothness set to work well with my preferred speed of drawing but pen pressure isn’t an issue.