I have about 5 years of professional experience with AE and I've never had this problem before. Normally when you want to click and drag to grab a selection of points in a mask, you select one point and then proceed to drag a marquee around your desired points. Out of nowhere today, AE stopped functioning like this for me. Now when I try to click off of the mask it doesn't deselect. When I click and drag somewhere completely away from the mask it drags the point points nearest to my cursor. when I double click away from the mask it still send the mask into "transform mode". I'm wondering if I may have accidentally hit a hot key that change the mask editing mode or auto select mode.
I posted a screen capture video of the problem. Thanks for your help.