i think, this is just the way, rectangles work.Diagonally pull left up and right down
you can always edit the mask by hitting V or activating the selection tool then double click on the mask to move it around with the mouse or arrow keys.
...No for some bizarre it's just started happening today halfway through a batch of images, I always draw masks from top right to bottom left but for some reason I can't even pull the mask in that direction instead it draws a mask in the opposite direction outside of the image.
I'm sure it's just a keyboard shortcut I've accidently hit.
I can't tweek each image - as I have hundreds to do for this comp
interesting, i always draw left top to right bottom, so i didn't even know, but i also never could shift-draw squares the other direction...
I am having a similar issue where I hold shift to transform a mask it will not work properly as it is not holding its constraints for either scale, or rotation. Very weird and frustrating.