I've had this problem pop up several times over the last year and I can never find a solution for it. When I try to use the pen tool I will start the line and then when I create a new anchor point the one before moves randomly. I can't create a single continuous line with the pen tool because of this. I've attached a screen grab of the issue (this was supposed to be a single line drawn with the pen tool, but it's created 5 because of all the migrating anchor points). Has anyone had this issue and figured out a solution to fix it?
Unfortunately I don't know of a solution, but perhaps there is some setting you could change if you go to Edit > Preferences... > Drawing.
I haven't had any luck with the drawing settings so far. Also tried uninstalling and reinstalling Animate, but that didn't do anything to get rid of the issue. I'll continue messing with settings and see if anything comes of it.