Windows occasionally "stick" a bit when dragging between windows monitors even with the same scaling on both screens. There are a bunch of keyboard shortcuts that are very reliable though. Windows Key + Shift + Direction: left/right instantly moves windows between displays, up maximizes, down un-maximizes and then minimizes. Windows Key + left/right (so without shift) also docks windows to the left or right of the same screen, and this feature is what makes windows also "stick" when dragging them from one screen to another.

I also recommend you check your display settings. If your windows aren't the same vertical size, then your overall desktop isn't a rectangle, it'll be some other polygon, and that means there are corners between the screens that your mouse can get stuck in.