Pencil strokes disappearing

Arrg, so so frustrated! I got an iPad Pro for Christmas, and have been trying to use it for work - handwriting in the GoodNotes app. I've put palm rejection on and have a palm rest pad. However, while I'm writing, my pencil strokes (from the stylus) are often just deleted. particularly when I do something 'wavy' like an 'm' or a ) or something. It's so frustrating as I have to rewrite the text 2 or 3 times before it takes. Has anyone else had this issue? is it a palm rest thing? Help!!!